Board Thread:ROBLOX help and discussion/@comment-26381561-20160606235420/@comment-5903643-20180717145028

Check your Internet connection. A slow Internet connection is the main cause of lag, since Roblox is online all the time.

If your game successfully loads but moves at the speed of the snail, it's most likely due to your computer, especially if it's over 7 years old. Lower your graphics quality and possibly upgrade your computer's graphics card.

Otherwise, blame the Roblox servers. They can fill up like a busy city square.