Sudden Performance Drop with Blender Viewport and Interface

I’m on Windows 10, Nvidia GT 740M. Blender viewport and interface has slowed to a crawl ;_; The console says, “Warning! Legacy WGL is unable to select between OpenGL versions. found bundled python: file path” I know my drivers are updated, I tried a Blender 2.79 reinstall, and it’s worked on Windows 10 for over a month, so it’s not the “GPU is too old” nonsense that the bug is reported as. It’s been weird since the Windows update a week ago. Blender recognizes integrated graphics and recognizes CUDA. Maya and other softwares work just fine too, so it’s only Blender. Any ideas?

Hi, sometimes Windows update install new video driver too but it is not original Nvidia.
They are often crippled or broken.
Try clean install of the original Nvidia driver.
You can disable updating of video driver during Windows update.

Cheers, mib

Thanks, I had a tech team do a clean Nvidia driver install already (since it failed every update I tried to give it). That didn’t change anything on Blender. I decided to try a .zip file version of 2.79, and it runs perfectly fine. So, my guess is there was something in the app data folders that got corrupted and was messing it up. Phew, that scared me. I guess I’ll run it out of a folder until 2.8 comes out…

all blenders, no matter where, still look for appdata. settings are saved in version folders like the ones found next to the exe.

Hmmmm…I wonder what did it then. I think in one of the re- or un-installations, I did a full clean. That might have done it then.