Instructions
Reduce game settings. Sometimes, if your graphical settings are high, the game's frame rate will be reduced when there is a lot of action on screen and this can appear like lag. Open the options menu and try reducing the quality of graphical properties such as "Textures," "Shaders," "Lighting," "Shadows," "Terrain," and "Models." This should improve the frame rate.
Download all available updates. Installing the latest patch for "Starcraft 2" can help to improve lag if certain changes were made that effect online play. The Blizzard Downloader usually forces you to download the latest patch when you log on to your Battle.net account; however, if you are having trouble using the Blizzard Downloader, visit the official Blizzard Support site for troubleshooting information.
Turn off firewalls. Open the Control Panel and click on "System and Security." Click the option "Windows Firewall" to access and turn off the firewalls you have in place on your system. Although firewalls are intended to protect your computer, they can increase latency and slow down your connection.
Join games that are hosted by other players rather than hosting games yourself. If you have a slow internet connection, latency will be increased if other players connect to your machine when you host a game. To join another player's game, all you need to do is click on "Join A Game" in the "Custom Games" window on the multiplayer menu.
Close all non-essential programs while playing. Programs that access the internet such as antivirus software, download managers and instant messenger programs, can use up a lot of your system resources. By closing these applications, you can reduce the amount of lag you experience when playing "Starcraft 2."