Memorising Titan's "rotation" is never a bad thing, however you should be getting better fps on that rig, mine is much worse than yours and ive capped my fps at 30 and i can normally get 30 everywhere except in cities\towns and fates.

I use a utility called tune up utilities by AVG (it has a free trial) and it makes suggestions for my
PC to keep it running smoothly, perhaps it would be worth a try for you.

My specs for reference:

Core2duo at 3.2Ghz
4GB RAM
GTX 280