I FIGURED IT OUT!

[536861646f57]

So anyone who is having massive lag in the Battle for Whiterun quest, I figured out why. There are numerous scripts running simultaneously, and there are lines in the Skyrim.ini that change the update time of the scripts:

[Papyrus]

fUpdateBudgetMS=100

fExtraTaskletBudgetMS=100

fPostLoadUpdateTimeMS=100

Now, I had them all set to 1000, which is 1 second. 1 second will make your framerate drop to 1 frame per second, or the Papyrus update time. To test my hypothesis I changed it to 500, then 300, then 100. I got 5, 7, and 10 FPS respectively until I passed Breezehome, which then my frame rate shot back up to 60.

If you want the CW Battle for Whiterun quest to be playable, I suggest you change all three to

[Papyrus]

fUpdateBudgetMS=10

fExtraTaskletBudgetMS=10

fPostLoadUpdateTimeMS=10

You SHOULD get proper FPS now. If not, let me know!