A commit with a big number of files (2k file changes) causes lazyjj to freeze for a couple of seconds

[melsharnou-chwy]

I have a commit in my history that has ~2k files that changed, it's mostly some files that get uploaded to s3, it causes lazyjj to lag a lot when moving to display this commit, or if it's the head of the main branch it causes moving to the main branch to lag for a couple of seconds as well.

[peso]

lazyjj is currently single threaded and expect all jj operations to complete quickly. Any jj operation taking longer than 100 ms will be noticable by users. One operation that often causes UI lag is a change with a large diff. That could be many files or many lines of difference.

One way of improving user experience, would be to do diff rendering on a separate thread. Another to allow users to disable diff view, or only display it when requested.

[dotdash]

@melsharnou-chwy Could you check whether the associated jj action (basically jj show for that change) takes a long time on its own, or whether lazyjj adds a noticeable overhead on top?

@peso not showing the diff by default is definitely on my todo list. I often don't care about it, and the slowdowns can be super annoying.