Your post is not clear enough and we need you to be as specific as possible so we need to get more information so other forum users will be able to help you with accurate information.
What type of cables are you using to connect the Slingbox to the TV source, Component, composite, S-video or coaxial? Are you using a satellite box or cable box? Which is the upload/download speed at home? Have you tried a different computer?
Please reply will all the information about the settings and connections of your Slingbox so we can help you with this.