paste it
Agreed.
But there are some things you can try.
Press F12 three times to set clip to minimum. This often helps on Macs that seem memory starved for some reason.
Also, you can try pressing F8 to put the game into "low quality" mode.
At the very extreme, you can type these into the chat bar:
/trees low
/flora low
...each of which will help with performance in different ways by uglying up the game.
The game isn't really optimized for older machines yet. I'll do that closer to alpha or after alpha.