diff --git a/Cargo.toml b/Cargo.toml
index 5a2433c..6792ae2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,6 +25,7 @@ mimalloc = "0.1"
 regex = "1.11"
 tungstenite = "0.26"
 socket2 = "0.5"
+postcard = { version = "1.1", features = ["use-std"] }
 clap = { version = "4.4", features = ["derive"] }
 
 [dependencies.reqwest]
diff --git a/src/device/cart_rom.rs b/src/device/cart_rom.rs
index 96afe9a..600461f 100644
--- a/src/device/cart_rom.rs
+++ b/src/device/cart_rom.rs
@@ -85,9 +85,8 @@ pub fn dma_read(
                 device.rdram.mem[(dram_addr + i) as usize ^ device.byte_swap];
 
             device.ui.saves.romsave.0.insert(
-                (cart_addr + i).to_string(),
-                serde_json::to_value(device.rdram.mem[(dram_addr + i) as usize ^ device.byte_swap])
-                    .unwrap(),
+                cart_addr + i,
+                device.rdram.mem[(dram_addr + i) as usize ^ device.byte_swap],
             );
         }
     }
@@ -139,8 +138,7 @@ pub fn load_rom_save(device: &mut device::Device) {
         return;
     }
     for (key, value) in device.ui.saves.romsave.0.iter() {
-        device.cart.rom[key.parse::<usize>().unwrap()] =
-            serde_json::from_value(value.clone()).unwrap()
+        device.cart.rom[*key as usize] = *value
     }
 }
 
diff --git a/src/ui.rs b/src/ui.rs
index 0fd4ac8..8e6c425 100644
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -142,7 +142,7 @@ impl Ui {
                 sram: (Vec::new(), false),
                 flash: (Vec::new(), false),
                 mempak: (Vec::new(), false),
-                romsave: (serde_json::Map::new(), false),
+                romsave: (std::collections::HashMap::new(), false),
             },
             pak_audio: audio::PakAudio {
                 mempak: include_bytes!("../data/mempak.wav").to_vec(),
diff --git a/src/ui/storage.rs b/src/ui/storage.rs
index ea3a561..8015726 100644
--- a/src/ui/storage.rs
+++ b/src/ui/storage.rs
@@ -27,7 +27,7 @@ pub struct Saves {
     pub sram: (Vec<u8>, bool),
     pub flash: (Vec<u8>, bool),
     pub mempak: (Vec<u8>, bool),
-    pub romsave: (serde_json::Map<String, serde_json::Value>, bool),
+    pub romsave: (std::collections::HashMap<u32, u8>, bool),
 }
 
 fn get_save_type(game_id: &str) -> Vec<SaveTypes> {
@@ -142,7 +142,7 @@ pub fn load_saves(ui: &mut ui::Ui, netplay: &mut Option<netplay::Netplay>) {
             // can't do romsaves with the current netplay implementation
             let romsave = std::fs::read(&mut ui.paths.romsave_file_path);
             if romsave.is_ok() {
-                ui.saves.romsave.0 = serde_json::from_slice(romsave.unwrap().as_ref()).unwrap();
+                ui.saves.romsave.0 = postcard::from_bytes(romsave.unwrap().as_ref()).unwrap();
             }
         }
     }
@@ -203,8 +203,8 @@ pub fn load_saves(ui: &mut ui::Ui, netplay: &mut Option<netplay::Netplay>) {
 }
 
 fn write_rom_save(ui: &ui::Ui) {
-    let f = std::fs::File::create(ui.paths.romsave_file_path.clone()).unwrap();
-    serde_json::to_writer(f, &ui.saves.romsave.0).unwrap();
+    let data = postcard::to_stdvec(&ui.saves.romsave.0).unwrap();
+    std::fs::write(ui.paths.romsave_file_path.clone(), data).unwrap();
 }
 
 pub fn write_saves(ui: &ui::Ui, netplay: &Option<netplay::Netplay>) {