Windows 7 Home Premium 64 bit on an HP Pavilion quad core APU and 8GB RAM + 1TB HD.
Firefox Version 47.0
Adblock Plus 2.7.3 (no custom filters)
The problem is (and I checked it before posting, by disabling 'ALL' addons, and enabling them 1 at a time, then restarting Firefox), Firefox freezes for about 15 seconds when Adblock Plus is enabled.
I first disabled every addon installed, then enabled each one and restarted Firefox, everything went fine until I enabled Adblock Plus, then as soon as Firefox started it froze for about 15 seconds with the CPU resource nearly hit 92% (using the windows cpu gadget), then after the 15 seconds Firefox resumed operation, to test it again, I left the other addons, and only disabled Adblock Plus, and when Firefox restarted, everything went fine, no freezes, which indicates it an Adblock Plus problem.
The additional addons I have installed are as listed below:-
Adblock Plus popup addon
Avast online security
Even with all these enabled and Adblock disabled, everything works fine, but enable Adblock Plus and Firefox temporarily freezes for about 15s.