diff --git a/build.Dockerfile b/build.Dockerfile
index 2521d83..21ca4cc 100644
--- a/build.Dockerfile
+++ b/build.Dockerfile
@@ -29,6 +29,7 @@ ENV PATH="/osxcross/bin:$PATH" \
     CARGO_TARGET_AARCH64_APPLE_DARWIN_LINKER="oa64-clang" \
     CARGO_TARGET_AARCH64_APPLE_DARWIN_AR="llvm-ar-19" \
     CROSS_COMPILE="setting-this-to-silence-a-warning-" \
+    SHROOMS_CFLAGS="-flto" \
     RC_PATH="llvm-rc-19" \
     RUSTFLAGS="-Lnative=/xwin/crt/lib/x86_64 -Lnative=/xwin/sdk/lib/um/x86_64 -Lnative=/xwin/sdk/lib/ucrt/x86_64" \
     MACOSX_DEPLOYMENT_TARGET="14.5"
diff --git a/build.rs b/build.rs
index 6335468..c478485 100644
--- a/build.rs
+++ b/build.rs
@@ -8,9 +8,17 @@ fn main() -> Result<(), Box<dyn Error>> {
     }
 
     println!("cargo::rerun-if-changed=shrooms-vb-core");
-    cc::Build::new()
+
+    let mut builder = cc::Build::new();
+    let _ = builder.try_flags_from_environment("SHROOMS_CFLAGS");
+    let opt_level = if builder.get_compiler().is_like_msvc() {
+        2
+    } else {
+        3
+    };
+    builder
         .include(Path::new("shrooms-vb-core/core"))
-        .opt_level(2)
+        .opt_level(opt_level)
         .flag_if_supported("-fno-strict-aliasing")
         .define("VB_LITTLE_ENDIAN", None)
         .define("VB_SIGNED_PROPAGATE", None)