If your video memory is filling up, then you need to turn down somethings. Full video ram will have an adverse effect on the overall performance of the game.
1) Do not preload textures into video ram.
2) Set the maximum texture size down one notch at a time, until you have some free video ram.
3) If you only have 512MB of ram, you need to do one of two things.
3a) Either set the meaximum texure size to 256 or
3b) Disable skins in the game.