memory issues + low fps?

ive been getting some bad fps spikes were my fps will go way down to 4-10 and stay there for a while. i talked to my friend and he told me to increase my virtual memory i did that just increases the time of good fps but i still get an fps spike after about 2 full 13 round games.. i decided id check the task manager while i was lagging on CF and my computer was barely using half my physical ram.. so somethin isnt right here besides i was able to play with great fps before the mutation mode came out. is there a solution to this.. btw ive already got all the settings to low but then again my comp is about 5 years old lol but still i dont see why it would go down.

ooh and then when my fps is low i get stock on almost everything and start rising off the floor.. and then get the error " incorrect player info" lol that would be nice not to have xD