If there is to much running on the phone, this can cause your problem. The same goes for if the service provider/carrier is having data issues or you have a data slowdown/cut off limit. Which most do.
Try turning off (actually closing out of the app) the other programs you aren't using at the time. Then in the case of programs like that, you should only be running one of them at a time. Otherwise expect problems. Also, if you are running any of it through the browser instead of individual apps, the browsers cache could be overly full and slowing you down. Lastly, make sure that all the apps you are using are actually updated.