Keeping a PC clean will always increase its performance.
Using an antivirus that uses less memory will always increase a PC's performance. (Compared to a memeory hungry anti-virus)

Doing good housekeeping will also maintain system performance.
Keep the registry clean and organised.

Limiting facter, as you rightfully mentioned is RAM for 32 bit systems.

Whan can also help?
Use readyboost for Windows 7;
Have an SD card slot?
Put a fast SD card in it and set it up for Windows7 readyboost.
Have some Fast USB sticks, and also set them up for readyboost.
Windows 7 can use up to 4 devices with 4GB each for readyboost.

Even my high end system, (as all my systems) have 3 USB slots filled with USB sticks on readyboost. (+ the SD card, makes 4X4 is 16GB available for readyboost.)

When HD swapping?
Only 2 sollutions possible. Reduce Poly count or reduce texture size.

Or render at slightly less settings.

 

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!