Good news, kind of found a fix
It is very weird Idk if you have your rendering graphics mode in the Studio settings set to Vulkan or not, but I just switched to Direct3D11 and it fixed it. There is definitely some very major bugs going on with Vulkan 1.3 and Roblox as of rn, but in (non-playing mode) in Studio for me D3D11 is extremely jittery whilst Vulkan runs smooth.
comparison:
Vulkan runs smooth (but contains various rendering bugs), D3D11 jitters way too much and unstable for editing (not when playing)