This is weird, bear with me while I explain. I love website blocking, I use it all the time. When I have website blocking on but I do not have Mozilla Firefox running I get a lot of lag in the system, mouse stutters and jumps, and general degradation of performance. When I launch Firefox it all goes away and everything runs normal. This does not happen with any browser but Firefox. If I have IE or Chrome running but no Firefox I get the performace hit. If I have them all running, no performance hit. If I shut them all down except Firefox no performance hit. If I shut down Firefox the degradation comes back immediately. When website blocking is active Core 0 of my 8350 Vishera octo-core is pegged at 100%. The other 7 cores operate normally. Core 0 (the first core) stays pegged at 100% no matter if a browser is running or not. Performance does not seem to be degraded noticably as long as Firefox is running even though Core 0 is maxed out. When I disable website blocking all the performance issues disappear and the system runs exactly as it should. With website blocking disabled Core 0 goes back to a normal, variable state and is no longer pegged at 100%. Another strange aspect is that nothing of MBAM or it's website blocking module shows up in Task Manager as using a lot of clock cycles. So it was a real pain to isolate the culprit and determine where the problem was coming from. With everything off (browsers and any other programs) and the computer idling Task Manager would show the system at 99% free with nothing spiking any processor clock cycles at all. Yet Core 0 would be pegged at 100% and the laggy performance degradation would still be occurring until Mozilla was launched. Then Core 0 would still be pegged but everything seemed to work as it should. It's like the website blocking module is looking for a browser to work against and not finding one it loops hard. But again, ONLY with Firefox, starting any other browser had no effect one way or the other. The system is running an ASUS Sabertooth 900FX motherboard, an AMD 8350 eight core processor and 16 GB of RAM. So it's got plenty of available resources. The OS is Win7 x64. I'm using CoreTemp and the CoreTemp desktop gadget to monitor the processor state and temperatures. I just turn off website blocking when I don't have Firefox running and turn it back on when I use any browser but I have to launch Firefox as well as whatever other browser I want to use if I want website blocking active. Usually I don't bother because I don't surf with anything but Firefox due to add-ons like ABP and No-Script. I use the other browsers for HTML controlled local nodes like routers, firewalls, cameras, etc. so they're not really a threat. It's not a big deal and as soon as I close Firefox the lag reminds me to disable website blocking. It's an easy workaround and I'm not complaining- I'm describing the situation to you to help you diagnose these lag issues that website blocking seems to be causing. If my efforts aren't helpful then feel free to ignore them.