Rendering my gameplay clip makes it laggy

After I navigate to "Deliver" tab, render then play the .mov file, I can see its laggy. The gamplay itself (before putting it in Davinci) isn't laggy and when I play the .mp4 file of it I cannot see any framedrop at all. But after i add all my clips to davinci and render them I can clearly see it's not as smooth as the gameplay initially was. What can i do?

Nothing but getting a simpler editing software.
DR can't handle VFR files reliably, having been developed for camera files. Check your clips with MediaInfo, I bet they are VFR (variable frame rates).

If they are VFR your best option is to probably use ffmpeg to convert them to a constant frame rate matching your timeline framerate so that frames are interpolated to be equidistant in time. Also probably using some mezzanine codec like cineform / hdnx / prores as intermediate to avoid too many re-compression artefacts.

I'd also be curious to see if changing the retime mode to "optical flow" with a good motion estimation method improves things or not.