Email sends taking forever

Not sure what is happening but our email sends starting around our Nov 12th email send are taking hours longer than they used to. They used to finish sending by 5:30a-6a when we started the send at 1am. What is causing this? Is anyone else experiencing this?

For example this morning 12/3 we scheduled an email to start sending at 1am, it finished sending at 8:27am ( sent to 9902 tags)

Email sent 12/29 started at 1am finished at 10:32am (11795 tags)
Email sent 12/26 started at 1am finished at 8:32am ( 11845 tags)
Email sent 11/18 started at 1am finished at 9:39am (9928 tags)