Yeah I did try running it at even lower settings through some FPS improvement scripts I found.

Barely an improvement, only jumped up from 10-25ish max, in heavy fights around 19ish and it goes down.

But I'll give the dxlevel a shot later on.

Here are some screens (ran in 1024x768 windowed):
The ones with the Task Manager show hl2.exe using around 50-60% of CPU power with Steam and System Idle using at least 10-20%.