slow performance when running neovim with a theme

[aneeshdurg]

Using neovim with a dark theme is too slow to be considered usable. Theme I'm using: moloki.

When launching neovim without my config (nvim -u NONE) the issue goes away.

I suspect this is because neovim is continually trying to redraw the background if the background is a different color.

[shohey1226]

I've seen this on Vim8 too. I tried to find dark background and dracula theme is okay for the performance. I'm curious why this happens.

colorscheme dracula 
set background=dark

[aneeshdurg]

If I had to suggest a fix without even looking at the code (so it might be totally wrong) , maybe the current background color could be cached and further requests to change the background can be ignored if it is the same.

Iirc tmux does something similar, which is why some vim themes don't render perfectly on it.

[tsl0922]

This maybe an upstream issue. Can you reproduce it with the xterm.js demo app and provide a chrome perf profile like what I did in xtermjs/xterm.js#1677?

[tsl0922]

I've upgraded xterm.js to 3.8.0, please check if it works.

[shohey1226]

@tsl0922 Thank you. Just checked and looks much better. If the width of window is bigger, like 296x62, then it becomes a bit slow. But I think it's usable to have vim theme now.

[aneeshdurg]

It's still not usable when using with fullscreen, but yeah, with a smaller window size it is somewhat usable.

[3ightbit]

I have some performance issues similar to what you describe. They are most noticeable with line/page redraws and when using Firefox. I think I found out that the slow down is introduced with this commit: 8ff3d31. I may try to look more into it later.

[tsl0922]

Please test the 1.6.0 release, and try if the webgl renderer (-t rendererType=webgl) helps.