diff --git a/proto/backend.proto b/proto/backend.proto
index 280f6d6bd..bcbad1ba2 100644
--- a/proto/backend.proto
+++ b/proto/backend.proto
@@ -99,10 +99,10 @@ message BackendOutput {
         GetCardOut get_card = 38;
         Empty update_card = 39;
         int64 add_card = 40;
-        string get_deck_config = 41;
+        bytes get_deck_config = 41;
         int64 add_or_update_deck_config = 42;
-        string all_deck_config = 43;
-        string new_deck_config = 44;
+        bytes all_deck_config = 43;
+        bytes new_deck_config = 44;
         Empty remove_deck_config = 45;
         Empty before_upload = 47;
         bool register_tags = 48;
@@ -434,7 +434,7 @@ message CloseCollectionIn {
 }
 
 message AddOrUpdateDeckConfigIn {
-    string config = 1;
+    bytes config = 1;
     bool preserve_usn_and_mtime = 2;
 }
 
diff --git a/pylib/anki/rsbackend.py b/pylib/anki/rsbackend.py
index 2449fbab8..e67b463c2 100644
--- a/pylib/anki/rsbackend.py
+++ b/pylib/anki/rsbackend.py
@@ -510,10 +510,10 @@ class RustBackend:
 
     def get_deck_config(self, dcid: int) -> Dict[str, Any]:
         jstr = self._run_command(pb.BackendInput(get_deck_config=dcid)).get_deck_config
-        return json.loads(jstr)
+        return orjson.loads(jstr)
 
     def add_or_update_deck_config(self, conf: Dict[str, Any], preserve_usn) -> None:
-        conf_json = json.dumps(conf)
+        conf_json = orjson.dumps(conf)
         id = self._run_command(
             pb.BackendInput(
                 add_or_update_deck_config=pb.AddOrUpdateDeckConfigIn(
@@ -527,13 +527,13 @@ class RustBackend:
         jstr = self._run_command(
             pb.BackendInput(all_deck_config=pb.Empty())
         ).all_deck_config
-        return json.loads(jstr)
+        return orjson.loads(jstr)
 
     def new_deck_config(self) -> Dict[str, Any]:
         jstr = self._run_command(
             pb.BackendInput(new_deck_config=pb.Empty())
         ).new_deck_config
-        return json.loads(jstr)
+        return orjson.loads(jstr)
 
     def remove_deck_config(self, dcid: int) -> None:
         self._run_command(pb.BackendInput(remove_deck_config=dcid))
diff --git a/rslib/src/backend/mod.rs b/rslib/src/backend/mod.rs
index 7452a624e..4178373db 100644
--- a/rslib/src/backend/mod.rs
+++ b/rslib/src/backend/mod.rs
@@ -717,15 +717,15 @@ impl Backend {
         Ok(card.id.0)
     }
 
-    fn get_deck_config(&self, dcid: i64) -> Result<String> {
+    fn get_deck_config(&self, dcid: i64) -> Result<Vec<u8>> {
         self.with_col(|col| {
             let conf = col.get_deck_config(DeckConfID(dcid), true)?.unwrap();
-            Ok(serde_json::to_string(&conf)?)
+            Ok(serde_json::to_vec(&conf)?)
         })
     }
 
     fn add_or_update_deck_config(&self, input: AddOrUpdateDeckConfigIn) -> Result<i64> {
-        let mut conf: DeckConf = serde_json::from_str(&input.config)?;
+        let mut conf: DeckConf = serde_json::from_slice(&input.config)?;
         self.with_col(|col| {
             col.transact(None, |col| {
                 col.add_or_update_deck_config(&mut conf, input.preserve_usn_and_mtime)?;
@@ -734,14 +734,12 @@ impl Backend {
         })
     }
 
-    fn all_deck_config(&self) -> Result<String> {
-        self.with_col(|col| {
-            serde_json::to_string(&col.storage.all_deck_config()?).map_err(Into::into)
-        })
+    fn all_deck_config(&self) -> Result<Vec<u8>> {
+        self.with_col(|col| serde_json::to_vec(&col.storage.all_deck_config()?).map_err(Into::into))
     }
 
-    fn new_deck_config(&self) -> Result<String> {
-        serde_json::to_string(&DeckConf::default()).map_err(Into::into)
+    fn new_deck_config(&self) -> Result<Vec<u8>> {
+        serde_json::to_vec(&DeckConf::default()).map_err(Into::into)
     }
 
     fn remove_deck_config(&self, dcid: i64) -> Result<()> {