diff --git a/libquickjs-sys/build.rs b/libquickjs-sys/build.rs
index 9a6796f..aaa45f0 100644
--- a/libquickjs-sys/build.rs
+++ b/libquickjs-sys/build.rs
@@ -114,7 +114,10 @@ fn main() {
         .flag_if_supported("-Wno-cast-function-type")
         .flag_if_supported("-Wno-implicit-fallthrough")
         .flag_if_supported("-Wno-enum-conversion")
-        .opt_level(0);
+        // The interpreter dispatch loop is the hottest code in every host;
+        // -O2 matches the official QuickJS Makefile. (This sat at -O0 from a
+        // 2021 bring-up experiment — a ~3-5x interpreter slowdown on MIPS.)
+        .opt_level(2);
 
     if is_psp {
         build
diff --git a/libquickjs-sys/src/lib.rs b/libquickjs-sys/src/lib.rs
index 6e92cca..ad7edc0 100644
--- a/libquickjs-sys/src/lib.rs
+++ b/libquickjs-sys/src/lib.rs
@@ -357,6 +357,11 @@ extern "C" {
     /// immediately, never retain it. Used by the 3D host (gfx3d.rs) to read mesh
     /// + command buffers handed down from JS.
     pub fn JS_GetArrayBuffer(ctx: *mut JSContext, psize: *mut size_t, obj: JSValue) -> *mut u8;
+
+    /// Cycle-collector trigger threshold (bytes allocated since the last run;
+    /// refcounting reclaims acyclic garbage regardless). Default is 256 KB.
+    pub fn JS_SetGCThreshold(rt: *mut JSRuntime, gc_threshold: size_t);
+    pub fn JS_RunGC(rt: *mut JSRuntime);
 }
 
 /// Custom allocator hooks so QuickJS can use the host (Rust/PSP) allocator