diff --git a/epaint/src/mutex.rs b/epaint/src/mutex.rs
index 2d8e4cb2..bd2cef4a 100644
--- a/epaint/src/mutex.rs
+++ b/epaint/src/mutex.rs
@@ -7,201 +7,205 @@ compile_error!("Either feature \"single_threaded\" or \"multi_threaded\" must be
 
 // ----------------------------------------------------------------------------
 
-/// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
-#[cfg(feature = "multi_threaded")]
-#[derive(Default)]
-pub struct Mutex<T>(parking_lot::Mutex<T>);
-
-/// The lock you get from [`Mutex`].
 #[cfg(feature = "multi_threaded")]
 #[cfg(not(debug_assertions))]
-pub use parking_lot::MutexGuard;
+mod mutex_impl {
+    /// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
+    #[derive(Default)]
+    pub struct Mutex<T>(parking_lot::Mutex<T>);
+
+    /// The lock you get from [`Mutex`].
+    pub use parking_lot::MutexGuard;
+
+    impl<T> Mutex<T> {
+        #[inline(always)]
+        pub fn new(val: T) -> Self {
+            Self(parking_lot::Mutex::new(val))
+        }
+
+        #[inline(always)]
+        pub fn lock(&self) -> MutexGuard<'_, T> {
+            self.0.lock()
+        }
+    }
+}
 
-/// The lock you get from [`Mutex`].
 #[cfg(feature = "multi_threaded")]
 #[cfg(debug_assertions)]
-pub struct MutexGuard<'a, T>(parking_lot::MutexGuard<'a, T>, *const ());
+mod mutex_impl {
+    /// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
+    #[derive(Default)]
+    pub struct Mutex<T>(parking_lot::Mutex<T>);
 
-#[cfg(all(debug_assertions, feature = "multi_threaded"))]
-#[derive(Default)]
-struct HeldLocks(Vec<*const ()>);
+    /// The lock you get from [`Mutex`].
+    pub struct MutexGuard<'a, T>(parking_lot::MutexGuard<'a, T>, *const ());
 
-#[cfg(all(debug_assertions, feature = "multi_threaded"))]
-impl HeldLocks {
-    fn insert(&mut self, lock: *const ()) {
-        // Very few locks will ever be held at the same time, so a linear search is fast
-        assert!(
-            !self.0.contains(&lock),
-            "Recursively locking a Mutex in the same thread is not supported"
-        );
-        self.0.push(lock);
+    #[derive(Default)]
+    struct HeldLocks(Vec<*const ()>);
+
+    impl HeldLocks {
+        #[inline(always)]
+        fn insert(&mut self, lock: *const ()) {
+            // Very few locks will ever be held at the same time, so a linear search is fast
+            assert!(
+                !self.0.contains(&lock),
+                "Recursively locking a Mutex in the same thread is not supported"
+            );
+            self.0.push(lock);
+        }
+
+        #[inline(always)]
+        fn remove(&mut self, lock: *const ()) {
+            self.0.retain(|&ptr| ptr != lock);
+        }
     }
 
-    fn remove(&mut self, lock: *const ()) {
-        self.0.retain(|&ptr| ptr != lock);
+    thread_local! {
+        static HELD_LOCKS_TLS: std::cell::RefCell<HeldLocks> = Default::default();
+    }
+
+    impl<T> Mutex<T> {
+        #[inline(always)]
+        pub fn new(val: T) -> Self {
+            Self(parking_lot::Mutex::new(val))
+        }
+
+        pub fn lock(&self) -> MutexGuard<'_, T> {
+            // Detect if we are recursively taking out a lock on this mutex.
+
+            // use a pointer to the inner data as an id for this lock
+            let ptr = (&self.0 as *const parking_lot::Mutex<_>).cast::<()>();
+
+            // Store it in thread local storage while we have a lock guard taken out
+            HELD_LOCKS_TLS.with(|held_locks| {
+                held_locks.borrow_mut().insert(ptr);
+            });
+
+            MutexGuard(self.0.lock(), ptr)
+        }
+    }
+
+    impl<T> Drop for MutexGuard<'_, T> {
+        fn drop(&mut self) {
+            let ptr = self.1;
+            HELD_LOCKS_TLS.with(|held_locks| {
+                held_locks.borrow_mut().remove(ptr);
+            });
+        }
+    }
+
+    impl<T> std::ops::Deref for MutexGuard<'_, T> {
+        type Target = T;
+
+        #[inline(always)]
+        fn deref(&self) -> &Self::Target {
+            &self.0
+        }
+    }
+
+    impl<T> std::ops::DerefMut for MutexGuard<'_, T> {
+        #[inline(always)]
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            &mut self.0
+        }
     }
 }
 
-#[cfg(all(debug_assertions, feature = "multi_threaded"))]
-thread_local! {
-    static HELD_LOCKS_TLS: std::cell::RefCell<HeldLocks> = Default::default();
-}
-
 #[cfg(feature = "multi_threaded")]
-impl<T> Mutex<T> {
-    #[inline(always)]
-    pub fn new(val: T) -> Self {
-        Self(parking_lot::Mutex::new(val))
-    }
+mod rw_lock_impl {
+    /// The lock you get from [`RwLock::read`].
+    pub use parking_lot::RwLockReadGuard;
 
-    #[cfg(debug_assertions)]
-    pub fn lock(&self) -> MutexGuard<'_, T> {
-        // Detect if we are recursively taking out a lock on this mutex.
+    /// The lock you get from [`RwLock::write`].
+    pub use parking_lot::RwLockWriteGuard;
 
-        // use a pointer to the inner data as an id for this lock
-        let ptr = (&self.0 as *const parking_lot::Mutex<_>).cast::<()>();
+    /// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
+    #[derive(Default)]
+    pub struct RwLock<T>(parking_lot::RwLock<T>);
 
-        // Store it in thread local storage while we have a lock guard taken out
-        HELD_LOCKS_TLS.with(|held_locks| {
-            held_locks.borrow_mut().insert(ptr);
-        });
+    impl<T> RwLock<T> {
+        #[inline(always)]
+        pub fn new(val: T) -> Self {
+            Self(parking_lot::RwLock::new(val))
+        }
 
-        MutexGuard(self.0.lock(), ptr)
-    }
+        #[inline(always)]
+        pub fn read(&self) -> RwLockReadGuard<'_, T> {
+            self.0.read()
+        }
 
-    #[inline(always)]
-    #[cfg(not(debug_assertions))]
-    pub fn lock(&self) -> MutexGuard<'_, T> {
-        self.0.lock()
-    }
-}
-
-#[cfg(debug_assertions)]
-#[cfg(feature = "multi_threaded")]
-impl<T> Drop for MutexGuard<'_, T> {
-    fn drop(&mut self) {
-        let ptr = self.1;
-        HELD_LOCKS_TLS.with(|held_locks| {
-            held_locks.borrow_mut().remove(ptr);
-        });
-    }
-}
-
-#[cfg(debug_assertions)]
-#[cfg(feature = "multi_threaded")]
-impl<T> std::ops::Deref for MutexGuard<'_, T> {
-    type Target = T;
-
-    #[inline(always)]
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-#[cfg(debug_assertions)]
-#[cfg(feature = "multi_threaded")]
-impl<T> std::ops::DerefMut for MutexGuard<'_, T> {
-    #[inline(always)]
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.0
-    }
-}
-
-// ---------------------
-
-/// The lock you get from [`RwLock::read`].
-#[cfg(feature = "multi_threaded")]
-pub use parking_lot::RwLockReadGuard;
-
-/// The lock you get from [`RwLock::write`].
-#[cfg(feature = "multi_threaded")]
-pub use parking_lot::RwLockWriteGuard;
-
-/// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
-#[cfg(feature = "multi_threaded")]
-#[derive(Default)]
-pub struct RwLock<T>(parking_lot::RwLock<T>);
-
-#[cfg(feature = "multi_threaded")]
-impl<T> RwLock<T> {
-    #[inline(always)]
-    pub fn new(val: T) -> Self {
-        Self(parking_lot::RwLock::new(val))
-    }
-
-    #[inline(always)]
-    pub fn read(&self) -> RwLockReadGuard<'_, T> {
-        self.0.read()
-    }
-
-    #[inline(always)]
-    pub fn write(&self) -> RwLockWriteGuard<'_, T> {
-        self.0.write()
+        #[inline(always)]
+        pub fn write(&self) -> RwLockWriteGuard<'_, T> {
+            self.0.write()
+        }
     }
 }
 
 // ----------------------------------------------------------------------------
-// `atomic_refcell` will panic if multiple threads try to access the same value
-
-/// The lock you get from [`Mutex`].
-#[cfg(not(feature = "multi_threaded"))]
-pub use atomic_refcell::AtomicRefMut as MutexGuard;
-
-/// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
-#[cfg(not(feature = "multi_threaded"))]
-#[derive(Default)]
-pub struct Mutex<T>(atomic_refcell::AtomicRefCell<T>);
 
 #[cfg(not(feature = "multi_threaded"))]
-impl<T> Mutex<T> {
-    #[inline(always)]
-    pub fn new(val: T) -> Self {
-        Self(atomic_refcell::AtomicRefCell::new(val))
-    }
+mod mutex_impl {
+    // `atomic_refcell` will panic if multiple threads try to access the same value
 
-    /// Panics if already locked.
-    #[inline(always)]
-    pub fn lock(&self) -> MutexGuard<'_, T> {
-        self.0.borrow_mut()
+    /// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
+    #[derive(Default)]
+    pub struct Mutex<T>(atomic_refcell::AtomicRefCell<T>);
+
+    /// The lock you get from [`Mutex`].
+    pub use atomic_refcell::AtomicRefMut as MutexGuard;
+
+    impl<T> Mutex<T> {
+        #[inline(always)]
+        pub fn new(val: T) -> Self {
+            Self(atomic_refcell::AtomicRefCell::new(val))
+        }
+
+        /// Panics if already locked.
+        #[inline(always)]
+        pub fn lock(&self) -> MutexGuard<'_, T> {
+            self.0.borrow_mut()
+        }
     }
 }
 
-// ---------------------
-
-/// The lock you get from [`RwLock::read`].
 #[cfg(not(feature = "multi_threaded"))]
-pub use atomic_refcell::AtomicRef as RwLockReadGuard;
+mod rw_lock_impl {
+    // `atomic_refcell` will panic if multiple threads try to access the same value
 
-/// The lock you get from [`RwLock::write`].
-#[cfg(not(feature = "multi_threaded"))]
-pub use atomic_refcell::AtomicRefMut as RwLockWriteGuard;
+    /// The lock you get from [`RwLock::read`].
+    pub use atomic_refcell::AtomicRef as RwLockReadGuard;
 
-/// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
-#[cfg(not(feature = "multi_threaded"))]
-#[derive(Default)]
-pub struct RwLock<T>(atomic_refcell::AtomicRefCell<T>);
+    /// The lock you get from [`RwLock::write`].
+    pub use atomic_refcell::AtomicRefMut as RwLockWriteGuard;
 
-#[cfg(not(feature = "multi_threaded"))]
-impl<T> RwLock<T> {
-    #[inline(always)]
-    pub fn new(val: T) -> Self {
-        Self(atomic_refcell::AtomicRefCell::new(val))
-    }
+    /// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
+    #[derive(Default)]
+    pub struct RwLock<T>(atomic_refcell::AtomicRefCell<T>);
 
-    #[inline(always)]
-    pub fn read(&self) -> RwLockReadGuard<'_, T> {
-        self.0.borrow()
-    }
+    impl<T> RwLock<T> {
+        #[inline(always)]
+        pub fn new(val: T) -> Self {
+            Self(atomic_refcell::AtomicRefCell::new(val))
+        }
 
-    /// Panics if already locked.
-    #[inline(always)]
-    pub fn write(&self) -> RwLockWriteGuard<'_, T> {
-        self.0.borrow_mut()
+        #[inline(always)]
+        pub fn read(&self) -> RwLockReadGuard<'_, T> {
+            self.0.borrow()
+        }
+
+        /// Panics if already locked.
+        #[inline(always)]
+        pub fn write(&self) -> RwLockWriteGuard<'_, T> {
+            self.0.borrow_mut()
+        }
     }
 }
 
 // ----------------------------------------------------------------------------
 
+pub use mutex_impl::{Mutex, MutexGuard};
+pub use rw_lock_impl::{RwLock, RwLockReadGuard, RwLockWriteGuard};
+
 impl<T> Clone for Mutex<T>
 where
     T: Clone,
@@ -211,6 +215,8 @@ where
     }
 }
 
+// ----------------------------------------------------------------------------
+
 #[cfg(test)]
 mod tests {
     use crate::mutex::Mutex;
diff --git a/sh/check.sh b/sh/check.sh
index 873958ae..76140f0e 100755
--- a/sh/check.sh
+++ b/sh/check.sh
@@ -20,6 +20,9 @@ cargo doc -p egui_web --target wasm32-unknown-unknown --lib --no-deps --all-feat
 
 (cd emath && cargo check --no-default-features)
 (cd epaint && cargo check --no-default-features --features "single_threaded")
+(cd epaint && cargo check --no-default-features --features "multi_threaded")
+(cd epaint && cargo check --no-default-features --features "single_threaded" --release)
+(cd epaint && cargo check --no-default-features --features "multi_threaded" --release)
 (cd egui && cargo check --no-default-features --features "multi_threaded")
 (cd eframe && cargo check --no-default-features --features "egui_glow")
 (cd epi && cargo check --no-default-features)