Using count for Set Membership Check
Checkout this benchmark shows count is faster than find - https://quick-bench.com/q/F_JiLDSu-7tQVgb-pHqPSoDxQsc That's for a container of a smaller size, I don't think that is that relevant here.

If you have a user-level macro benchmark that proves this is an optimization I'll reopen, but just fudging with a micro benchmark to change numbers doesn't work Also, your benchmark seems influenced by noise, rerunning gives https://quick-bench.com/q/F_JiLDSu-7tQVgb-pHqPSoDxQsc That is, clearing the cache and rerunning generates new results. Your link now proves the contrary of what you've said.
Instead of find and comparing to end(), using count to check for membership in the std::unordered_set. which is more efficient.