FPS Drop Out of Nowhere

[#M|A#Wolf]

I usually have a fps range of 170 - 230, but today I launched AC and I saw my fps being in the 80 - 95 range. What could have provoked this? As far as I remember I haven't done any changes to the graphics this week; I also tried restarting me laptop but the fps stayed.

Any ideas? I'm on a Macbook Snow Leopard version 10.6.5

Here are is my graphics info if it is necessary:

NVIDIA GeForce 9400M:

Chipset Model: NVIDIA GeForce 9400M
Type: GPU
Bus: PCI
VRAM (Total): 256 MB
Vendor: NVIDIA (0x10de)
Device ID: 0x0863
Revision ID: 0x00b1
ROM Revision: 3462
Displays:

Color LCD:
Resolution: 1280 x 800
Pixel Depth: 32-Bit Color (ARGB8888)
Main Display: Yes
Mirror: Off
Online: Yes
Built-In: Yes

Display Connector:
Status: No Display Connected