I made a competitor to GitHubs UI for Pull Requests (codeapprove.com)

It’s built in Vue. My first 5 or 6 attempts at writing the diff viewer were very slow when things got big. I optimized this a lot and now I’m pretty proud of how snappy it is.

I’m not saying this as a plug (this is mostly a passion project not a big business) but to say that it’s possible to make a snappy GitHub PR UI using a frontend framework on top of GitHub’s own APIs. You just have to care. It’s not clear that they care.