It's not that, I mainly play on the web and it gets really laggy when you load large maps. It seems to work fine though on the windows version.
The windows downloaded version also lags. I think it's just because of how many enemies there is, there's not a lot you can do.
I don't think it's that, the honeysmasher levels have a huge load of enemies, but I've found no lag. I think it is due to the map sizing.