My laptop is not exactly a gaming engine either, but when I set it like this, PS runs okay:
- Anti-Aliasing, Anisotropic Filtering, Shadows, Bloom, HDR, VBO, Loader Cache: all OFF
- Color Depth 32, Particles Shaders Medium (experiment wiht the shaders, sometimes "low" is worse then "medium" for some strange reasons.
- I have texture to "high" but turning them lower will also give a performance boost
- Weather: just try if your system can handle it. Some crash.
And when you get a high fps hit Hydlaa, look at the floor.

Hope this helps a bit.
(You could also turn your settings way down until you are satisfied and then increase them one after one until you identify what helps most.)
Best,
Minks