Your graphics card has to draw the image to the monitor at least 20 times per second to get smooth motion. Any slower, and you get the dreaded "jerkovision", like an old movie. Hence the importance of a good graphics card. A good one, like the Nvidea Riva TNT2 Ultra (which I use) can exceed 120 frames per second at a resolution of 800x600

The number of video frames displayed per unit of time, usually in seconds.

This is measured in FPS. The framerate is how many times a second the screen is updated. Rendering many objects, like chimneys, can cause a drop in the framerate. When the framerate drops very low, the game appears to be slowing down. [ edit

number of frames in a given space of time