Many people experience this. The Dev team knows. Last I saw posted by a mod, they weren't sure what was causing it. Regardless they know it is an issue, have confirmed they are working it. Rather, "wworking" on it.A search of the the bug forums should net the answers the mods have previously posted about it, though it would be nice to get an update.
Hey mods, any chance we can get some word on actual progress beyond, "we know about it?" Maybe? Pretty please? With a cherry on top?