When I was using it I used to notice a slight delay on some actions (maximizing a window, doing alt-tab, opening the task bar, etc.), that I never had on Gnome Classic.
It must be said, however, Cinnamon is really nice.
At second thought, I noticed this until I disabled desktop effects, you might want to make sure that wasn't the delay you noticed as that delay is configurable and artificial.
It must be said, however, Cinnamon is really nice.