Well another thing to think about though is that depending on the game this card may not be faster than the 8600GT (Desktop or Notebook) as although a lot of the specs are higher one part is slower. The 8600GT has 8 Pixel shaders while the 525M has 4 meaning it can't shade pixels at the same rate and this may lower framerates in certain games compared to the 8600GT.
Max shader rate for each card (8600GT = 4.32GP/s, 8600M GT = 3.8GP/s, 525M 2.4GP/s). Given that your framerates are about 53% of what you had and the GPU's power in shading is about 53% of what the older GPU was I would say this game is likely highly dependent on Pixel Shading.