I would invest in a bluetooth gamepad for your PC. For this, and other games like it (the Tomb Raider series; arcade and SNES emulation; etc.). A good one is twenty to thirty bucks, and better ones have force feedback and rechargeable batteries. I consider it a main part of my PC, as I use the windows half exclusively for gaming.

The swimming thing is inexcusable.

AntiAliasing: The game does, indeed, offer AntiAliasing in-game. It’s called “Multisampling”. Also, you can use the nVidia control panel, or nHancer, to “Enhance in-game AA settings” instead of overriding them; this is how I’m using 8x AA in this game, instead of the highest in-game default of 4x.

This brings my framerate down to around 45-60 average, with 37fps being my lowest dip (viewpointing).