Bugzilla

This bug is very similar to bug 1900466, but this bug is about the `WeakMap.set` part, not about the proxy creation part.

We spend 3x as much time as Chrome inside `WeakMap.set`. This shows up on Sp3-Vue-TodoMVC and Sp3-NewsSite-Nuxt. On both tests making Firefox as fast as Chrome on this function would reduce its overal time by 0.6%.

It's possible that `WeakMap.set` is slower today than when bug 1900466 was filed.

Chrome: https://share.firefox.dev/4h2PRys (211 samples in Builtins_WeakMapPrototypeSet)
FF: https://share.firefox.dev/3No7qv8 (648 samples in WeakMapObject::set)

```js
function createReactiveObject(target, isReadonly, baseHandlers, collectionHandlers, proxyMap) {
            if (!(0, _vue_shared__WEBPACK_IMPORTED_MODULE_1__.Kn)(target)) {
                if (false) {}
                return target;
            }
            if (target["__v_raw"] && !(isReadonly && target["__v_isReactive"])) {
                return target;
            }
            const existingProxy = proxyMap.get(target);
            if (existingProxy) {
                return existingProxy;
            }
            const targetType = getTargetType(target);
            if (targetType === 0) {
                return target;
            }
            const proxy = new Proxy(target, targetType === 2 ? collectionHandlers : baseHandlers);
            proxyMap.set(target, proxy);
            return proxy;
        }
```

This bug is very similar to bug 1900466, but this bug is about the `WeakMap.set` part, not about the proxy creation part.

We spend 3x as much time as Chrome inside `WeakMap.set`. This shows up on Sp3-Vue-TodoMVC and Sp3-NewsSite-Nuxt. On both tests making Firefox as fast as Chrome on this function would reduce the overall runtime of this subtest in Firefox by 0.6%.

It's possible that `WeakMap.set` is slower today than when bug 1900466 was filed.

Chrome: https://share.firefox.dev/4h2PRys (211 samples in Builtins_WeakMapPrototypeSet)
FF: https://share.firefox.dev/3No7qv8 (648 samples in WeakMapObject::set)

```js
function createReactiveObject(target, isReadonly, baseHandlers, collectionHandlers, proxyMap) {
            if (!(0, _vue_shared__WEBPACK_IMPORTED_MODULE_1__.Kn)(target)) {
                if (false) {}
                return target;
            }
            if (target["__v_raw"] && !(isReadonly && target["__v_isReactive"])) {
                return target;
            }
            const existingProxy = proxyMap.get(target);
            if (existingProxy) {
                return existingProxy;
            }
            const targetType = getTargetType(target);
            if (targetType === 0) {
                return target;
            }
            const proxy = new Proxy(target, targetType === 2 ? collectionHandlers : baseHandlers);
            proxyMap.set(target, proxy);
            return proxy;
        }
```