This sometimes happens at the start of the game.  It eventually goes away.  If anything, it's helpful during those early few minutes when there really isn't much to do except scout.

When the game lags it speeds up aftewards to make up for it from my observations.  If there is a lot of lag at the beginning the game will go very fast.

One evidence of this is if you participate in a 2 hour game, as measured by your clock, it will report a 2 hour game in the stats, and indeed it was 2 hours worth of gameplay, despite the fact that there was probably bits of lag scattered through the game.

...so there are options to slow down the game speed.