Poor ventilation and cooling just sounds like a problem with that specific model of laptop, if you can link us to it that would be great. Not to mention if you buy a laptop that has good specs, but are doing stuff that it was never intended to do (heavy gaming and game design) then overheating is just a problem you have to deal with as you made a not so good purchase for what you do in that case.
The other problems you are experiencing are really an issue of how you, yourself, are using the laptop. Viruses dont just magically appear on a computer, youve not been careful enough when downloading stuff to be aware of the viruses, torrents are notorious for stuff like that. Your best bet if you are running into speed issues with the laptop is changing the HDD to an SSD (all newer macbooks and Imacs have some form of SSD in them for the operating system so they function faster). Like I said before, these issues you are running into with the laptop seem to just stem from bad purchasing on your end.