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Like it the features, but its true taht it takes a lot of CPU on my system! Please improve!

Это отзыв для предыдущей версии этого дополнения (1.0.4.1). 

I have never seen this even on old CPUs. Uncheck enable interest filter in options > general > enable interest filter as this is really the only thing that uses much CPU at all.

If you have Firebug installed, see also https://www.mozdev.org/bugs/show_bug.cgi?id=17877
although I don't know if Firebug still has this bug.