So I've identified part of the problem, which appears to be not just Avast.
Windows 7 update KB288409 is designed to improve browser performance on Internet Explorer 11. I've since removed this and it now takes about 2mins or less to load the UI.
On a side point, don't update to Vuze 5.2 - if you've already done so, please note that your system may now be infected with "Browser.Spigot.A" and "Optional.Conduit.A" malware, which changes search settings on your browsers, and sometimes even encrypts or steals your files! Run a scan with
MalwareBytes' Anti-Malware just to be sure, as well as check for "Spigot" / "Bunndle" directories installed and "Savings" apps that might have been added to your browser. Then install and run
HitmanPro's 30-day trial, and download to desktop and run
ComboFix after that. If they don't find the folders, look for them using Windows Explorer and delete them; I can assue you they're most likely malware and not legit.
However, DO NOT search and remove folders named "Conduit" unless these programs tell you to - some of it is actually not malware and part of the functionality of certain programs like Adobe AIR...
I'd strongly recommend you purchase the first two programs, as they can both run in conjunction with Avast without software conflicts.