GitHub was very snappy in the early days. I remember how refreshing I found GitHub when it was new. I don't know when but sometime after 2020 it has just been going downhill.

The same could be said of Jira.

I could switch on the dev console in the Browser, and see which one loads the largest amount of Javascript, but I'd be disappointed with both.

I'm 40 years old and I've never heard or experienced such things :)