diff --git a/Cargo.toml b/Cargo.toml
index 6cf91e2..cbc6152 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,7 +6,7 @@ members = [
 [package]
 name = "bitcode"
 authors = [ "Cai Bear", "Finn Bear" ]
-version = "0.6.3"
+version = "0.6.4"
 edition = "2021"
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/SoftbearStudios/bitcode"
@@ -38,6 +38,7 @@ zstd = "0.13.0"
 [features]
 derive = [ "dep:bitcode_derive" ]
 std = [ "serde?/std", "glam?/std", "arrayvec?/std" ]
+unsound = [] # use benign undefined behavior for more performance. Miri will detect this. See GitHub Wiki "Security".
 default = [ "derive", "std" ]
 
 [package.metadata.docs.rs]
diff --git a/src/derive/vec.rs b/src/derive/vec.rs
index f692fd7..05ec81d 100644
--- a/src/derive/vec.rs
+++ b/src/derive/vec.rs
@@ -53,28 +53,33 @@ macro_rules! unsafe_wild_copy {
     ([$T:ident; $N:ident], $src:ident, $dst:ident, $n:ident) => {
         debug_assert!($n != 0 && $n <= $N);
 
-        let page_size = 4096;
-        let read_size = core::mem::size_of::<[$T; $N]>();
-        let within_page = $src as usize & (page_size - 1) < (page_size - read_size) && cfg!(all(
-            // Miri doesn't like this.
-            not(miri),
-            // cargo fuzz's memory sanitizer complains about buffer overrun.
-            // Without nightly we can't detect memory sanitizers, so we check debug_assertions.
-            not(debug_assertions),
-            // x86/x86_64/aarch64 all have min page size of 4096, so reading past the end of a non-empty
-            // buffer won't page fault.
-            any(target_arch = "x86", target_arch = "x86_64", target_arch = "aarch64")
-        ));
+        // Note: Neither Miri nor the fuzzer's memory sanitizer like this feature. We prevent
+        // the latter from seeing it with `not(debug_assertions)`.
+        #[cfg(all(feature = "unsound", not(debug_assertions)))]
+        {
+            let page_size = 4096;
+            let read_size = core::mem::size_of::<[$T; $N]>();
+            let within_page = $src as usize & (page_size - 1) < (page_size - read_size) && cfg!(any(
+                // x86/x86_64/aarch64 all have min page size of 4096, so reading past the end of a non-empty
+                // buffer won't page fault.
+                target_arch = "x86",
+                target_arch = "x86_64",
+                target_arch = "aarch64",
+            ));
 
-        if within_page {
-            *($dst as *mut core::mem::MaybeUninit<[$T; $N]>) = core::ptr::read($src as *const core::mem::MaybeUninit<[$T; $N]>);
-        } else {
-            #[cold]
-            unsafe fn cold<T>(src: *const T, dst: *mut T, n: usize) {
-                src.copy_to_nonoverlapping(dst, n);
+            if within_page {
+                *($dst as *mut core::mem::MaybeUninit<[$T; $N]>) = core::ptr::read($src as *const core::mem::MaybeUninit<[$T; $N]>);
+            } else {
+                #[cold]
+                unsafe fn cold<T>(src: *const T, dst: *mut T, n: usize) {
+                    src.copy_to_nonoverlapping(dst, n);
+                }
+                cold($src, $dst, $n);
             }
-            cold($src, $dst, $n);
         }
+
+        #[cfg(any(not(feature = "unsound"), debug_assertions))]
+        $src.copy_to_nonoverlapping($dst, $n);
     }
 }
 pub(crate) use unsafe_wild_copy;