Seeing as the server ticks every 600ms doing so so much more, refreshing punishments every 2 minutes is negligible? (I think he's doing it either 2 seconds or 2 minutes, I'd do it every 2 minutes)
I mean how often do people talk? Probably more often than once per two minutes. Bans should be checked for on login sure, you don't want people that are banned to even log in