doc: add ReflectConstruct to known perf issues

PR-URL: nodejs#50111
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

doc/contributing/primordials.md

@@ -122,6 +122,9 @@ performance of code in Node.js.
 * `SafePromiseAny`
 * `SafePromiseRace`
 * `SafePromisePrototypeFinally`: use `try {} finally {}` block instead.
+* `ReflectConstruct`: Also affects `Reflect.construct`.
+  `ReflectConstruct` creates new types of classes inside functions.
+  Instead consider creating a shared class. See [nodejs/performance#109](https://github.com/nodejs/performance/issues/109).
 
 In general, when sending or reviewing a PR that makes changes in a hot code
 path, use extra caution and run extensive benchmarks.