Program Contour slows syntax highlighting to a crawl

[DexterLagan]

Windows 11, DrRacket 8.6.0.9 (same problem has been there since 8.6 release). Having Program Contour enabled slows syntax coloring to a few lines per second, vs. nearly instant on my system. Disabling program contour while the coloring is happening fixes the problem. Tested on a single Racket file with several thousand LOC. Problem does not seem to appear on Apple Silicon and Linux.

[rfindler]

I tried to reproduce this but wasn't able to. Can you offer a screen recording or a more precise set of instructions?

What I tried was opening drracket/private/unit and then just watched the colors in the contour and they seemed to appear at the same speed as the colors filled the buffer itself and that speed didn't seem to change if the contour was on or off. I also tried scrolling to the end and opening a string (which makes everything following that turn red) and it seems reasonably zippy.

[Olinn-IT-Tech]

I was able to run some more tests: on my X1 carbon gen 9, using the integrated Intel adapter, 4k resolution, DrRacket 8.7 is extremely slow all around with or without Contour enabled. When Contour is displayed, it's even slower to apply syntax highlighting. On my other system, Lenovo P16 with a discreet video card, it's fast with or without contour. I'll ping back if I find the difference, apart from the hardware.

[Olinn-IT-Tech]

Got more details: DrRacket becomes unusable on Windows 10/11 running on an Intel adapter, in 4k or more. Contour is very slow, and scrolling is slow in general. As soon as I switch to the nvidia discreet adapter, it runs at a decent speed. I'd chalk this up as poor performance of the integrated Intel chips in resolutions above 2-3k.