I know this sounds ridiculous, but it actually worked for me. My problems were:

* Lag spikes/delays while playing - occasionally attacks (mine and the monsters) don't appear, even though I can still move around the map. Then, all of a sudden, everything is sped up and it usually results in my death

* Computer freezing when going through TPs, banners or switching maps - the load screen would freeze and nothing works except for a hard reset. This was the biggest problem.

So, I followed these instructions - http://support.apple.com/kb/ht3964

It worked. All day yesterday I was lag free. Then, I went through a banner and it froze again, and when I reset my computer, the lag was back. So, I went through the instructions again (shutdown, unplug, wait, plug back in) and the lag went away again. Just thought I would let anyone else having this issue know what worked for me. While it's not a permanent solution, it did work. For a while at least.