Low framerate on good computer

I’m struggling to get more than 20 FPS in Gmod since I got a new computer. This computer can run battlefield 4 on high with 60 fps but Garry’s Mod struggles to get more than 20 no matter if my ingame settings are very high or very low. Why is this happening? My old computer ran it better.

CPU is intel core i7-4700mq
GPU is nvidia geforce gtx 770m / 3gb GDDR5

I just posted pretty much the same thing, but with somewhat worse specs and using linux.
My old iMac also ran it better than i do now

Heres the thread
http://forum.facepunch.com/showthread.php?t=1337685

maybe it is running on your IGP instead of your GPU?

when intel is used low fps
put
-force_vendor_id 0x10DE -force_device_id 0x1180
in launch options.
also force nvidia ingpu panel for hl2.exe
you wil lalso notice high shadow option become avalible

That worked well, thanks.