Looking for help with frame stuttering on new PC

I take it you did a fresh install of DbD on your new PC? Otherwise, clearing your DirectX shader cache may be of help.

DbD these days does attempt to build much of the shader cache on first launch, but in the first few sessions there can still be some freezes here and there when new shaders are loaded and cached mid-trial. So the issue could simply rectify itself as you play more and the shader cache has all the pertinent files.

Other than that, using VSync is generally not advisable, as it considerably increases input latency. If you cannot bear having screen tearing, consider some of the following: use FreeSync instead; use your graphics card's VSync implementation instead of DbD's; play the game in windowed mode where Windows will do low-latency syncing instead (windowed fullscreen unfortunately still has tearing on Windows 11 since it is treated as a fullscreen app); limit your framerate just below your monitor's refresh rate to decrease the VSync-induced input lag - since DbD only offers a few framerate presets, you'll likely have to use your GPU settings for this.

I will say that tearing is really not very noticeable at high framerates. The objectively best way to set up DbD for both performance and latency is using fullscreen mode, 120fps, and VSync off. Give this a try if you haven't already.