diff --git a/proto/anki/scheduler.proto b/proto/anki/scheduler.proto
index 5eefe0030..364bf50ad 100644
--- a/proto/anki/scheduler.proto
+++ b/proto/anki/scheduler.proto
@@ -51,7 +51,7 @@ service SchedulerService {
       returns (ComputeFsrsParamsResponse);
   rpc GetOptimalRetentionParameters(GetOptimalRetentionParametersRequest)
       returns (GetOptimalRetentionParametersResponse);
-  rpc ComputeOptimalRetention(ComputeOptimalRetentionRequest)
+  rpc ComputeOptimalRetention(SimulateFsrsReviewRequest)
       returns (ComputeOptimalRetentionResponse);
   rpc SimulateFsrsReview(SimulateFsrsReviewRequest)
       returns (SimulateFsrsReviewResponse);
@@ -409,16 +409,6 @@ message SimulateFsrsReviewResponse {
   repeated float daily_time_cost = 4;
 }
 
-message ComputeOptimalRetentionRequest {
-  repeated float params = 1;
-  uint32 days_to_simulate = 2;
-  uint32 max_interval = 3;
-  string search = 4;
-  double loss_aversion = 5;
-  repeated float easy_days_percentages = 6;
-  optional uint32 suspend_after_lapse_count = 7;
-}
-
 message ComputeOptimalRetentionResponse {
   float optimal_retention = 1;
 }
diff --git a/rslib/src/scheduler/fsrs/retention.rs b/rslib/src/scheduler/fsrs/retention.rs
index a0fc1cda9..c724709fb 100644
--- a/rslib/src/scheduler/fsrs/retention.rs
+++ b/rslib/src/scheduler/fsrs/retention.rs
@@ -1,18 +1,12 @@
 // Copyright: Ankitects Pty Ltd and contributors
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
-use std::sync::Arc;
-
-use anki_proto::scheduler::ComputeOptimalRetentionRequest;
+use anki_proto::scheduler::SimulateFsrsReviewRequest;
 use fsrs::extract_simulator_config;
-use fsrs::PostSchedulingFn;
 use fsrs::SimulatorConfig;
 use fsrs::FSRS;
 
-use super::simulator::apply_load_balance_and_easy_days;
 use crate::prelude::*;
 use crate::revlog::RevlogEntry;
-use crate::scheduler::states::load_balancer::parse_easy_days_percentages;
-use crate::search::SortMode;
 
 #[derive(Default, Clone, Copy, Debug)]
 pub struct ComputeRetentionProgress {
@@ -21,65 +15,16 @@ pub struct ComputeRetentionProgress {
 }
 
 impl Collection {
-    pub fn compute_optimal_retention(
-        &mut self,
-        req: ComputeOptimalRetentionRequest,
-    ) -> Result<f32> {
+    pub fn compute_optimal_retention(&mut self, req: SimulateFsrsReviewRequest) -> Result<f32> {
         let mut anki_progress = self.new_progress_handler::<ComputeRetentionProgress>();
         let fsrs = FSRS::new(None)?;
         if req.days_to_simulate == 0 {
             invalid_input!("no days to simulate")
         }
-        let revlogs = self
-            .search_cards_into_table(&req.search, SortMode::NoOrder)?
-            .col
-            .storage
-            .get_revlog_entries_for_searched_cards_in_card_order()?;
-        let p = self.get_optimal_retention_parameters(revlogs)?;
-        let learn_span = req.days_to_simulate as usize;
-        let learn_limit = 10;
-        let deck_size = learn_span * learn_limit;
-        let easy_days_percentages = parse_easy_days_percentages(req.easy_days_percentages)?;
-        let next_day_at = self.timing_today()?.next_day_at;
-        let post_scheduling_fn: Option<PostSchedulingFn> =
-            if self.get_config_bool(BoolKey::LoadBalancerEnabled) {
-                Some(PostSchedulingFn(Arc::new(
-                    move |card, max_interval, today, due_cnt_per_day, rng| {
-                        apply_load_balance_and_easy_days(
-                            card.interval,
-                            max_interval,
-                            today,
-                            due_cnt_per_day,
-                            rng,
-                            next_day_at,
-                            &easy_days_percentages,
-                        )
-                    },
-                )))
-            } else {
-                None
-            };
+        let (config, cards) = self.simulate_request_to_config(&req)?;
         Ok(fsrs
             .optimal_retention(
-                &SimulatorConfig {
-                    deck_size,
-                    learn_span: req.days_to_simulate as usize,
-                    max_cost_perday: f32::MAX,
-                    max_ivl: req.max_interval as f32,
-                    first_rating_prob: p.first_rating_prob,
-                    review_rating_prob: p.review_rating_prob,
-                    learn_limit,
-                    review_limit: usize::MAX,
-                    new_cards_ignore_review_limit: true,
-                    suspend_after_lapses: None,
-                    post_scheduling_fn,
-                    review_priority_fn: None,
-                    learning_step_transitions: p.learning_step_transitions,
-                    relearning_step_transitions: p.relearning_step_transitions,
-                    state_rating_costs: p.state_rating_costs,
-                    learning_step_count: p.learning_step_count,
-                    relearning_step_count: p.relearning_step_count,
-                },
+                &config,
                 &req.params,
                 |ip| {
                     anki_progress
@@ -88,7 +33,7 @@ impl Collection {
                         })
                         .is_ok()
                 },
-                None,
+                Some(cards),
             )?
             .clamp(0.7, 0.95))
     }
diff --git a/rslib/src/scheduler/fsrs/simulator.rs b/rslib/src/scheduler/fsrs/simulator.rs
index 144741f0a..133b3ff2c 100644
--- a/rslib/src/scheduler/fsrs/simulator.rs
+++ b/rslib/src/scheduler/fsrs/simulator.rs
@@ -115,10 +115,10 @@ fn create_review_priority_fn(
 }
 
 impl Collection {
-    pub fn simulate_review(
+    pub fn simulate_request_to_config(
         &mut self,
-        req: SimulateFsrsReviewRequest,
-    ) -> Result<SimulateFsrsReviewResponse> {
+        req: &SimulateFsrsReviewRequest,
+    ) -> Result<(SimulatorConfig, Vec<fsrs::Card>)> {
         let guard = self.search_cards_into_table(&req.search, SortMode::NoOrder)?;
         let revlogs = guard
             .col
@@ -170,7 +170,7 @@ impl Collection {
         let deck_size = converted_cards.len();
         let p = self.get_optimal_retention_parameters(revlogs)?;
 
-        let easy_days_percentages = parse_easy_days_percentages(req.easy_days_percentages)?;
+        let easy_days_percentages = parse_easy_days_percentages(&req.easy_days_percentages)?;
         let next_day_at = self.timing_today()?.next_day_at;
 
         let post_scheduling_fn: Option<PostSchedulingFn> =
@@ -217,12 +217,21 @@ impl Collection {
             learning_step_count: p.learning_step_count,
             relearning_step_count: p.relearning_step_count,
         };
+
+        Ok((config, converted_cards))
+    }
+
+    pub fn simulate_review(
+        &mut self,
+        req: SimulateFsrsReviewRequest,
+    ) -> Result<SimulateFsrsReviewResponse> {
+        let (config, cards) = self.simulate_request_to_config(&req)?;
         let result = simulate(
             &config,
             &req.params,
             req.desired_retention,
             None,
-            Some(converted_cards),
+            Some(cards),
         )?;
         Ok(SimulateFsrsReviewResponse {
             accumulated_knowledge_acquisition: result.memorized_cnt_per_day,
diff --git a/rslib/src/scheduler/service/mod.rs b/rslib/src/scheduler/service/mod.rs
index 1d5d1ccb4..e7d9a04eb 100644
--- a/rslib/src/scheduler/service/mod.rs
+++ b/rslib/src/scheduler/service/mod.rs
@@ -9,7 +9,6 @@ use anki_proto::generic;
 use anki_proto::scheduler;
 use anki_proto::scheduler::ComputeFsrsParamsResponse;
 use anki_proto::scheduler::ComputeMemoryStateResponse;
-use anki_proto::scheduler::ComputeOptimalRetentionRequest;
 use anki_proto::scheduler::ComputeOptimalRetentionResponse;
 use anki_proto::scheduler::FsrsBenchmarkResponse;
 use anki_proto::scheduler::FuzzDeltaRequest;
@@ -284,7 +283,7 @@ impl crate::services::SchedulerService for Collection {
 
     fn compute_optimal_retention(
         &mut self,
-        input: ComputeOptimalRetentionRequest,
+        input: SimulateFsrsReviewRequest,
     ) -> Result<ComputeOptimalRetentionResponse> {
         Ok(ComputeOptimalRetentionResponse {
             optimal_retention: self.compute_optimal_retention(input)?,
diff --git a/rslib/src/scheduler/states/load_balancer.rs b/rslib/src/scheduler/states/load_balancer.rs
index 7029bb1ba..915b0b8b3 100644
--- a/rslib/src/scheduler/states/load_balancer.rs
+++ b/rslib/src/scheduler/states/load_balancer.rs
@@ -277,7 +277,7 @@ impl LoadBalancer {
     }
 }
 
-pub(crate) fn parse_easy_days_percentages(percentages: Vec<f32>) -> Result<[EasyDay; 7]> {
+pub(crate) fn parse_easy_days_percentages(percentages: &[f32]) -> Result<[EasyDay; 7]> {
     if percentages.is_empty() {
         return Ok([EasyDay::Normal; 7]);
     }
@@ -300,7 +300,7 @@ pub(crate) fn build_easy_days_percentages(
         .into_iter()
         .map(|(dcid, conf)| {
             let easy_days_percentages =
-                parse_easy_days_percentages(conf.inner.easy_days_percentages)?;
+                parse_easy_days_percentages(&conf.inner.easy_days_percentages)?;
             Ok((dcid, easy_days_percentages))
         })
         .collect()
diff --git a/ts/routes/deck-options/FsrsOptions.svelte b/ts/routes/deck-options/FsrsOptions.svelte
index ef2487719..356437cb9 100644
--- a/ts/routes/deck-options/FsrsOptions.svelte
+++ b/ts/routes/deck-options/FsrsOptions.svelte
@@ -7,13 +7,9 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         ComputeRetentionProgress,
         type ComputeParamsProgress,
     } from "@generated/anki/collection_pb";
-    import {
-        ComputeOptimalRetentionRequest,
-        SimulateFsrsReviewRequest,
-    } from "@generated/anki/scheduler_pb";
+    import { SimulateFsrsReviewRequest } from "@generated/anki/scheduler_pb";
     import {
         computeFsrsParams,
-        computeOptimalRetention,
         evaluateParams,
         setWantsAbort,
     } from "@generated/backend";
@@ -26,7 +22,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import GlobalLabel from "./GlobalLabel.svelte";
     import { commitEditing, fsrsParams, type DeckOptionsState } from "./lib";
     import SpinBoxFloatRow from "./SpinBoxFloatRow.svelte";
-    import SpinBoxRow from "./SpinBoxRow.svelte";
     import Warning from "./Warning.svelte";
     import ParamsInputRow from "./ParamsInputRow.svelte";
     import ParamsSearchRow from "./ParamsSearchRow.svelte";
@@ -37,8 +32,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     export let openHelpModal: (String) => void;
     export let onPresetChange: () => void;
 
-    const presetName = state.currentPresetName;
-
     const config = state.currentConfig;
     const defaults = state.defaults;
     const fsrsReschedule = state.fsrsReschedule;
@@ -50,13 +43,8 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     let computeParamsProgress: ComputeParamsProgress | undefined;
     let computingParams = false;
     let checkingParams = false;
-    let computingRetention = false;
 
-    let optimalRetention = 0;
-    $: if ($presetName) {
-        optimalRetention = 0;
-    }
-    $: computing = computingParams || checkingParams || computingRetention;
+    $: computing = computingParams || checkingParams;
     $: defaultparamSearch = `preset:"${state.getCurrentNameForSearch()}" -is:suspended`;
     $: roundedRetention = Number($config.desiredRetention.toFixed(2));
     $: desiredRetentionWarning = getRetentionWarning(
@@ -65,19 +53,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     );
     $: retentionWarningClass = getRetentionWarningClass(roundedRetention);
 
-    let computeRetentionProgress:
-        | ComputeParamsProgress
-        | ComputeRetentionProgress
-        | undefined;
-
-    const optimalRetentionRequest = new ComputeOptimalRetentionRequest({
-        daysToSimulate: 365,
-        lossAversion: 2.5,
-    });
-    $: if (optimalRetentionRequest.daysToSimulate > 3650) {
-        optimalRetentionRequest.daysToSimulate = 3650;
-    }
-
     $: newCardsIgnoreReviewLimit = state.newCardsIgnoreReviewLimit;
 
     $: simulateFsrsRequest = new SimulateFsrsReviewRequest({
@@ -233,44 +208,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         }
     }
 
-    async function computeRetention(): Promise<void> {
-        if (computingRetention) {
-            await setWantsAbort({});
-            return;
-        }
-        if (state.presetAssignmentsChanged()) {
-            alert(tr.deckConfigPleaseSaveYourChangesFirst());
-            return;
-        }
-        computingRetention = true;
-        computeRetentionProgress = undefined;
-        try {
-            await runWithBackendProgress(
-                async () => {
-                    optimalRetentionRequest.maxInterval = $config.maximumReviewInterval;
-                    optimalRetentionRequest.params = fsrsParams($config);
-                    optimalRetentionRequest.search = `preset:"${state.getCurrentNameForSearch()}" -is:suspended`;
-                    optimalRetentionRequest.easyDaysPercentages =
-                        $config.easyDaysPercentages;
-                    const resp = await computeOptimalRetention(optimalRetentionRequest);
-                    optimalRetention = resp.optimalRetention;
-                    computeRetentionProgress = undefined;
-                },
-                (progress) => {
-                    if (progress.value.case === "computeRetention") {
-                        computeRetentionProgress = progress.value.value;
-                    }
-                },
-            );
-        } finally {
-            computingRetention = false;
-        }
-    }
-
     $: computeParamsProgressString = renderWeightProgress(computeParamsProgress);
-    $: computeRetentionProgressString = renderRetentionProgress(
-        computeRetentionProgress,
-    );
     $: totalReviews = computeParamsProgress?.reviews ?? undefined;
 
     function renderWeightProgress(val: ComputeParamsProgress | undefined): String {
@@ -285,22 +223,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         }
     }
 
-    function renderRetentionProgress(
-        val: ComputeRetentionProgress | undefined,
-    ): String {
-        if (!val) {
-            return "";
-        }
-        return tr.deckConfigIterations({ count: val.current });
-    }
-
-    function estimatedRetention(retention: number): String {
-        if (!retention) {
-            return "";
-        }
-        return tr.deckConfigPredictedOptimalRetention({ num: retention.toFixed(2) });
-    }
-
     async function computeAllParams(): Promise<void> {
         await commitEditing();
         state.save(UpdateDeckConfigsMode.COMPUTE_ALL_PARAMS);
@@ -390,49 +312,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     {/if}
 </div>
 
-<div class="m-2">
-    <details>
-        <summary>{tr.deckConfigComputeOptimalRetention()}</summary>
-
-        <SpinBoxRow
-            bind:value={optimalRetentionRequest.daysToSimulate}
-            defaultValue={365}
-            min={1}
-            max={3650}
-        >
-            <SettingTitle on:click={() => openHelpModal("computeOptimalRetention")}>
-                {tr.deckConfigDaysToSimulate()}
-            </SettingTitle>
-        </SpinBoxRow>
-
-        <button
-            class="btn {computingRetention ? 'btn-warning' : 'btn-primary'}"
-            disabled={!computingRetention && computing}
-            on:click={() => computeRetention()}
-        >
-            {#if computingRetention}
-                {tr.actionsCancel()}
-            {:else}
-                {tr.deckConfigComputeButton()}
-            {/if}
-        </button>
-
-        {#if optimalRetention}
-            {estimatedRetention(optimalRetention)}
-            {#if optimalRetention - $config.desiredRetention >= 0.01}
-                <Warning
-                    warning={tr.deckConfigDesiredRetentionBelowOptimal()}
-                    className="alert-warning"
-                />
-            {/if}
-        {/if}
-
-        {#if computingRetention}
-            <div>{computeRetentionProgressString}</div>
-        {/if}
-    </details>
-</div>
-
 <div class="m-2">
     <button class="btn btn-primary" on:click={() => (showSimulator = true)}>
         {tr.deckConfigFsrsSimulatorExperimental()}
diff --git a/ts/routes/deck-options/SimulatorModal.svelte b/ts/routes/deck-options/SimulatorModal.svelte
index c7d2e17e7..070bed4fa 100644
--- a/ts/routes/deck-options/SimulatorModal.svelte
+++ b/ts/routes/deck-options/SimulatorModal.svelte
@@ -16,9 +16,10 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import { SimulateSubgraph, type Point } from "../graphs/simulator";
     import * as tr from "@generated/ftl";
     import { renderSimulationChart } from "../graphs/simulator";
-    import { simulateFsrsReview } from "@generated/backend";
+    import { computeOptimalRetention, simulateFsrsReview } from "@generated/backend";
     import { runWithBackendProgress } from "@tslib/progress";
     import type {
+        ComputeOptimalRetentionResponse,
         SimulateFsrsReviewRequest,
         SimulateFsrsReviewResponse,
     } from "@generated/anki/scheduler_pb";
@@ -30,6 +31,8 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import EnumSelectorRow from "$lib/components/EnumSelectorRow.svelte";
     import { DeckConfig_Config_LeechAction } from "@generated/anki/deck_config_pb";
     import EasyDaysInput from "./EasyDaysInput.svelte";
+    import Warning from "./Warning.svelte";
+    import type { ComputeRetentionProgress } from "@generated/anki/collection_pb";
 
     export let shown = false;
     export let state: DeckOptionsState;
@@ -53,9 +56,14 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     let suspendLeeches = $config.leechAction == DeckConfig_Config_LeechAction.SUSPEND;
     let leechThreshold = $config.leechThreshold;
 
+    let optimalRetention: null | number = null;
+    let computingRetention = false;
+    let computeRetentionProgress: ComputeRetentionProgress | undefined = undefined;
+
     $: daysToSimulate = 365;
     $: deckSize = 0;
     $: windowSize = Math.ceil(daysToSimulate / 365);
+    $: processing = simulating || computingRetention;
 
     function movingAverage(y: number[], windowSize: number): number[] {
         const result: number[] = [];
@@ -75,14 +83,61 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         return arr1.map((value, index) => value + arr2[index]);
     }
 
-    async function simulateFsrs(): Promise<void> {
-        let resp: SimulateFsrsReviewResponse | undefined;
+    function estimatedRetention(retention: number): String {
+        if (!retention) {
+            return "";
+        }
+        return tr.deckConfigPredictedOptimalRetention({ num: retention.toFixed(2) });
+    }
+
+    function updateRequest() {
         simulateFsrsRequest.daysToSimulate = daysToSimulate;
         simulateFsrsRequest.deckSize = deckSize;
         simulateFsrsRequest.suspendAfterLapseCount = suspendLeeches
             ? leechThreshold
             : undefined;
         simulateFsrsRequest.easyDaysPercentages = easyDayPercentages;
+    }
+
+    function renderRetentionProgress(
+        val: ComputeRetentionProgress | undefined,
+    ): String {
+        if (!val) {
+            return "";
+        }
+        return tr.deckConfigIterations({ count: val.current });
+    }
+
+    $: computeRetentionProgressString = renderRetentionProgress(
+        computeRetentionProgress,
+    );
+
+    async function computeRetention() {
+        let resp: ComputeOptimalRetentionResponse | undefined;
+        updateRequest();
+        try {
+            await runWithBackendProgress(
+                async () => {
+                    computingRetention = true;
+                    resp = await computeOptimalRetention(simulateFsrsRequest);
+                },
+                (progress) => {
+                    if (progress.value.case === "computeRetention") {
+                        computeRetentionProgress = progress.value.value;
+                    }
+                },
+            );
+        } finally {
+            computingRetention = false;
+            if (resp) {
+                optimalRetention = resp.optimalRetention;
+            }
+        }
+    }
+
+    async function simulateFsrs(): Promise<void> {
+        let resp: SimulateFsrsReviewResponse | undefined;
+        updateRequest();
         try {
             await runWithBackendProgress(
                 async () => {
@@ -328,6 +383,39 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
                     {/if}
                 </details>
 
+                <div class="m-2">
+                    <details>
+                        <summary>{tr.deckConfigComputeOptimalRetention()}</summary>
+                        <button
+                            class="btn {computingRetention
+                                ? 'btn-warning'
+                                : 'btn-primary'}"
+                            disabled={!computingRetention && computing}
+                            on:click={() => computeRetention()}
+                        >
+                            {#if computingRetention}
+                                {tr.actionsCancel()}
+                            {:else}
+                                {tr.deckConfigComputeButton()}
+                            {/if}
+                        </button>
+
+                        {#if optimalRetention}
+                            {estimatedRetention(optimalRetention)}
+                            {#if optimalRetention - $config.desiredRetention >= 0.01}
+                                <Warning
+                                    warning={tr.deckConfigDesiredRetentionBelowOptimal()}
+                                    className="alert-warning"
+                                />
+                            {/if}
+                        {/if}
+
+                        {#if computingRetention}
+                            <div>{computeRetentionProgressString}</div>
+                        {/if}
+                    </details>
+                </div>
+
                 <button
                     class="btn {computing ? 'btn-warning' : 'btn-primary'}"
                     disabled={computing}
@@ -366,7 +454,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
                     {tr.deckConfigSaveOptionsToPreset()}
                 </button>
 
-                {#if simulating}
+                {#if processing}
                     {tr.actionsProcessing()}
                 {/if}