Literally everyone who has used Github to look at a pull request in say the last year has experienced the ridiculous performance issues. It's a constant laughing point on HN at this point. There is no way you don't know this. Inviting to take this to a private channel, along with the rest of your comment really, is simply standard corporate PR.

Yes agreed it's been a huge problem, and we shipped changes last week to address some of the gnarly p99 interactions. It doesn't fix everything and large PRs have a lot of room to be faster. It's still good to know where some worst performance issues are to see if there's anything particularly problematic or if a future change will help.