I know that GTA IV probably isn't the best game to judge a computers performance by, but I'm sure it feels slower since I've upgraded. If I'm driving a fast car in it, every few seconds the screen jerks slightly, like a slight pause. I've gone from a Intel Q6600 running at 3.4Ghz to a Intel Core i5 running at 3.8Ghz. I haven't changed the graphics card, a ATI 4870 1GB. I had to set to everything to medium, the shadows off and the draw distance and detail down to 15 or so anyway for it to run smoothly on the Q6600 and I haven't changed those settings. If anything, it should feel smoother after this so I'm not sure what's gone wrong. I've put the i5 back to stock settings in case my overclock was causing a problem but it runs the same. GTA has all the patches installed and WIndows 7 64-bit is fully updated, and I'm running the latest ATI catalyst drivers. I've even tried overclocking the 4870 in case it was that, but it started to get worse after it got to 815Mhz on the core speed. Anyone got any ideas as to what is causing this?