When you did your uninstall of Avast, did you also uninstall version 4.0 and 5.0 in Safe Mode? I know you have done several uninstalls/installs, but it is possible that you have remnants of older versions that could be causing the conflict. I would do a CLEAN install of build 594 to see if this resolves your problem. Make sure you reboot your machine after the install...I suggest 2 boots and make sure you have your AV and FW as trusted exclusions.
If you have done this already, then you need to check your FW for issues causing your conflict. This usually causes the slow surfing. BTW, please list your FW in your signature so others can help you as well. I am not familiar with your FW, but do you have a web shield in it that you can disable to see if this helps? You have disabled the AV in your FW...correct?
'till the latest version (before I used 5.0.0.590 Pre Release) everything worked normally.
I was using avast! Free 5 & Online Armor Free 4 for months without the slightest issue. Oh, yes, I had an issue few months ago when I installed Online Armor Free for the first time. The network at PC boot freezed, 'caused by the issue in OA Exlusion procedure. Anyway, I solved it in a few days.
I also use cFosSpeed, Internet Download Manager & Cacheman 7 on 7 Ultimate 32-bit.
Anyway, everything worked normally for months 'till the latest avast! update. So the issue must be there.
I tried literally everything, but the browsing speed turned to a crawl.
But, in the end, it doesn't matter to much. I installed avast! without Web Shield. Everything works normal again and the security wasn't compromised.
COMMON SENSE is still the best protection!
Thanks & enjoy!
I'll wait till the next avast! update...