Lately this has been slowing down Firefox. Pages loading very slowly. Firefox using a lot of processor time.(quick again after I disable it) I think it is a bit suspect. I have disabled it.
Don't know, how EPUBReader could cause such a problem. It seems, you suspect, that it includes a mining script. Rest assured, that this is not the case. EPUBReader is part of the Mozilla "recommended program" which only includes manually checked add-ons which meet the highest standards.
