How do I stop Counter Strike Source lagging in the game?
Maps might be causing problem because their files in your game directory is missing or corrupted. You can re-download the game to replace the maps. If you are playing on a custom map, the server you are connecting will load the map to you before you start the game. So there should be no problem there. Go to the games online options and make sure it is allows custom downloads from servers. To reduce the lag you can update to a faster internet connection or upgrade your PC. But more reasonable solutions would be that; you can try closing the programs running in the back like Virus Protection or Media, etc. Or you can try turning down the games graphic and audio settings. Or maybe try running the game more resonable resolution. These all should help.