Hello there,
I've been having some FPS issues since the big Westhill update. I have the max fps set to 75fps, and once I first start LFS it keeps 75.0fps all the time. As time passes the fps starts dropping and after an hour or two I am stuck at less than 30fps.

I am using a HP Pavilion g7-2003sm (i5-3210M, 3.1GHz, 6GB DDRIII, HD7670M 1GB). The game is running on dedicated GPU. I have the newest drivers. I have tried closing all background tasks, there are no scheduled tasks, so nothing that could be throttling. LFS is the only game this is happening in.

I am also using LFS Lazy, and I have activated the "GPU Usage" gadget (not sure if it's correct for switchable graphics though) since nothing else shows activity and it never goes over 60%.

Thermal throttling probably, check your temperatures while playing.

You can use this program, or anyone that you prefer.
http://openhardwaremonitor.org/

HP does have terrible cooling but I am sure that is not the issue. I cleaned it and changed the thermal paste recently.
The CPU runs at ~75°C (throttling at 105 or 115, not sure anymore), the GPU runs at less than 70°C.

Also, games that need much more PC resources don't get thermal throttling, so I don't think LFS would.

E: Checked a lot of times with multiple apps.