That seemed to do it. I slid the separator all the way down to hide the 3D view. The moment I saved the file, it released the GPU.

Thanks for the help!

64 bit. I actually ended up purchasing the Microsoft app version after having issues with the one offered on Sourceforge - both have issues.

I just tried the older version and it spikes to 90%, but not 100%

Seems there's a bit of an issue there as well for me.

The spikes below start when drawing ...

Just updated and started using the program again after about a year off. Now, when I try to modify a wall or even go to program preferences, my GPU pegs at 100% and the system slows to a crawl. CPU is fine, it's just the GPU that spikes.

Windows 10 x64
GeForce GT 740 on the latest driver (431.36 ...