I am finding every time I cast a large amount of spells the game will go to about 1 frame per 10 seconds to 1 min if I am watching the circular spell casting animation. If I go look somewhere else (to hide from the lag) then the game will somewhat survive and only lag like normal. Examples would be casting storm 3-4 times in the same spot or casting cold 7 or 8 times or mend a similar amount of times.
I am not sure how to fix it but it seems to be the massive amount of partials generated in the spell animation cause the computer to give up. I would prefer an option to completely eliminate all partials if I could play the game relatively lag free (if possible).