When questing with a group and we go to the cinematic portion where you answer the NPCs questions, I always see the group members faces in the bottom left of screen and then numbers pop up. 12, 99, 112, etc...seem random, what is that?

I know this should probably be asked in a different category, however, I would like to get some of the folks suggestions who play on different machines and different specs. I know eventually I have to get a new computer, but in the mean time, what are some ways I can improve performance. I have an Nvidia 9800 Geforce GT, CPU is about 3 years old. There is lag and stuttering and it is really distracting and takes me out of the gaming experience. I have everything set to low for graphics and turned off shadows. Anything else? Thanks