Need to find a good codec for Premiere Pro

Hello, I am having a problem like this.

Normally I would record 2 video with the Microsoft game bar, then join the two videos together (upper and lower half via mask). My experience when working in Premiere Pro (playback) is very smooth.

However, recently I switched to using xvid ro render for 1video (another one still recorded using game bar). And my experience in Premiere Pro (playback) is very laggy now, even though I adjusted the playback to 1/8. Playback can only play for a few seconds and be frozen.

In addition, the time for Premiere Pro to render is very different, I have a feeling that the render time of 2 videos recorded by game bar is faster than 1 video recorded by game bar + 1 video rendered by xvid. (Other parameters are the same (1080p, 60fps ...)

I want to know if my feeling is correct or not, how to fix it, or if someone can tell me how to get the codec used by the game bar (i using codec to render in a third-party).

Thanks for reading.