Why is the new Outlook Mail so slow?

Ever since Outlook got updated (some weeks ago), it's been running incredibly slow and lags my entire browser. Anyone else have this happen, and is there anything to fix this?

I agree, the new Outlook is slower, regardless if I'm using Edge or IE. Each mouse click is much slower. Even just moving my mouse down the list of messages is a slow experience. As I hover over a message, the message is supposed to highlight, but it takes too long to highlight it. This causes a significant delay when I try to click and open a message.

I have deleted temp files and cache, but that did not help. I have also tried disabling and re-installing AdBlock Plus, but that did not help either.