2 AM server crawl.
 

Every night at 2:00 AM eastern, there is a significant lag in the servers. This is post server switch. It generally lasts 10-20 minutes.

I believe that is when the daily maintenance happens. It's been that way for a long time. It's 3 AM crawl for me. :D

Alright. . . I'm willing to admit that it's probably the best time to do so, theres not many of us active on here past 1.

I agree. I'm usually done by 4:00.

IIRC it used to be at 5am EST.