“Perform” takes up the most.
I ran a script to count the parts, meshes, and unions and got this result:
— COMPLETE —
Parts: 2009
Meshes: 15
Unions: 14
Total: 2038
Likely an issue with your graphics driver. I have this happen occasionally and going full-screen usually fixes it. My “Perform” also goes nuclear when I move Roblox to my 1440p monitor, even though I have a gtx 1080ti. Seems like a Roblox bug to me but difficult to get an engineer to reproduce.