Run the game on full screen mode, not windowed mode.
Lower the resolution to something relatively acceptable, like 720p.
Close any open applications you have open on the computer, especially the Chrome browser that treats memory like how Grendel treats enemies.
Disable optional "features", like regional or alliance chat. That's one less background thread for the engine to run, less clutter on the screen, and pesky regional chat hoohahs. Disable other visual settings as well.