Freezing on Black Wyrm

[WarmMachine]

When fighting black wyrm the game will randomly freeze up for 2-4 seconds.  FPS is sticking around 15-20.  I have all the graphic settings turned down, I have even tried running in windowed mode with the lowest resolution.  Have tried to kill BW 5 times now and can never do enough dps when the game is frozen for 2-4 out of every 20 seconds and I unfreeze to find I died to an ae.