Even with the program problems you're having, this is actually pretty darn clean lol.
Have you already found the smoothing setting in the pen settings? If so, here's a few other things that might work, if you haven't tried them already!
- Try using any other browsers you have. (Personally, all my other browsers don't work with Oekaki, but Edge does.)
- Try using one of the other Oekaki versions, there's 2 others:
Oekaki settings- If you've been using it full screen or with a ton of tabs open, it might cause lag that messes with the strokes.
- Sometimes, updating tablet drivers may help.
Oekaki is pretty finicky, sometimes it stops working for me entirely and starts working later... for seemingly no reason? So, good luck with it! ^^''