TF2 only using ~30% CPU now…

[Superfantastic]

I'm getting only about 1/4 of the fps as I used to. Before a couple days ago, TF2 used about 80-100% CPU, giving me great frame rates. Now, the CPU usage dropped, and so did my fps…

I didn't change any settings, this seemingly happened overnight.

Using a 2012 rMBP w/ 8GB RAM.