You need a video editor for that. OBS is not one.
Everyone has their bias and preference of course. I like this one:
Shotcut is a free, open source, cross-platform video editor for Windows, Mac and Linux
shotcut.org
It's free, runs on anything, does a LOT, and it's easy enough (for me at least) to get started with.
Whatever you end up using, it should have a playback speed setting for each clip, that defaults at 1x. I find that 10x works well to zip through some boring stuff without missing anything, and get to the next interesting bit. Your mileage will definitely vary on that!
If you can't speed up just a section of a clip, you can split it into several clips, each with its own speed setting. Shotcut is like that. When you speed it up, it'll leave a gap that you need to close, and then you're (theoretically) done.