Slow performance on large files

[tyirvine]

I noticed whilst using Hungry Delete I was getting some slow performance. I was confused and thought it was VS Code but noticed when I disabled Hungry Delete deletion was fast again. I realized it's because I was working in a large file. For some reason however Hungry Delete works, line count influences it's speed. Or so it seems at least.

It wasn't really that big of a file though. Only 1000 lines of code (it's just a file that holds c arrays for drawing on an lcd). Anyways figured this was important enough to warrant raising an issue and fixing it!

Slow performance ⤵︎

Normal performance ⤵︎

It was difficult to show key presses but it sometimes takes a whole second when bogged down.