The fact you need for this program a reasonable computer goes without saying, as when a virus program now time everything is calculated parallel and must be checked. Therefore, it may also happen that the Internet speed decreases slightly and some images and animations to load longer need. The mentioned from other customers slow "Download has not yet occurred to me until now, and I invite every day larger quantities of data. The complaints about the virus scan I can not understand. The security now time takes time for me is a matter of course. That some people complain anyway and maybe aggravate other potential customers, the decision or the product advise is maybe not for everyone. Maybe should be this and let me think if they want to have a secure PC more or just a program like making fast fast it offers little security, but they should rather leave to other people the decision.
For this price, of course, you should think carefully about whether you want to invest this. I can only say that security today is an important issue and at least to the extent that such programs are used to give us a bit of security, although complete security will probably no longer be possible today, I think that one is largely with this program. In my view, strong buy recommendation!