I don't believe your RAM is involved here. I have ran into a similar situation as well. Though sometimes the game runs perfectly, npcs spawn like they should when they should. However then it begins to skip frames and even the music skips, npc's take FOREVER to spawn. Whats even more bizarre is that I am running better in Maximum vs Standard????

I am not sure what is going on because I run maximum fine but then when the skipping begins it lasts for a while and its pretty intolerable. I found a temporary fix I think. I changed the display settings from 32-bit color to 16-bit but I would prefer to put it back on 32-bit. I am going to check for driver updates for my NVidia card when I get out of work though I don't believe NVidia is the problem here, it seems as if the game is just not running correctly.