You have lots of RAM so RAM isn't a problem.
What I think you should do is turn off the swap file, restart the computer, make a new swap file to a specific size.
Go to control panel >> system >> advanced (tab) >> performance settings >> advanced (tab) >> virtual memory change
Select "no paging file" then hit set. Restart the computer. Go back to those settings and set it to an exact amount, mine is 1024 minimum and 1024 maximum.
After that is done, defrag the hard drive.
If everything went good, your hard drive before should look like this (blue is non-fragmented, red is fragmented, yellow is swap file):
The after should look like this:
The before picture is the screwed computer I mentioned (defrag doesn't even do anything on it). The after picture is my gaming computer. Notice how my good computer has 1 swap file area, but the crap computer has 3.