Low FPS on Garry's Mod

All other games seem to work on maximum settings, but Garry’s Mod seems to run really slowly, changing the quality settings doesn’t really help, specs are…

Operating System
MS Windows 7 Ultimate 64-bit
CPU
Intel Xeon W3570 @ 3.20GHz 61 °C
Bloomfield 45nm Technology
RAM
12.0GB Dual-Channel DDR3 @ 668MHz (9-9-9-24)
Motherboard
ASUSTeK Computer INC. P6T6 WS REVOLUTION (LGA1366) 50 °C
Graphics
Sony GDM-FW900 (1920x1200@120Hz)
DELL U2410 (1920x1200@59Hz)
DELL 1708FP (1280x1024@60Hz)
NVIDIA GeForce GTX 470
NVIDIA GeForce GTX 470
Hard Drives
250GB CRUCIAL_CT256M225 ATA Device (SATA)
250GB CRUCIAL_CT256M225 ATA Device (SATA)
977GB Western Digital WDC WD1002FAEX-00Y9A0 ATA Device (SATA) 33 °C
977GB Western Digital WDC WD1002FAEX-00Y9A0 ATA Device (SATA) 31 °C
Optical Drives
HL-DT-ST DVD-RAM GSA-H30N ATA Device
ATAPI iHAS124 B ATA Device
Audio
SB X-Fi Xtreme Audio

define slowly.

there’s slow as in “9 fps can’t do shit” and then there’s “it only runs at 50 fps that’s too slow for my rig!!!” which happens too often