Norton is a Resource hog and not a good fit on budget systems. Pop ups you can solve with Adblock Pro https
/adblockplus.org/. Run Norton and it should handle the viruses for you... slowly.
Here is how you remove Optimizer Pro, you will need to do that first than deal with the other issues.
Consider installing Malware byte it will get what Norton misses if not remove the Malware faster, this is what slows you system down in the first place.
Also if your using Internet Explorer, consider switching to Firefox or Chrome both are less likely to infect and are overall faster to use.
When installing Programs always pay close attention, never let it do a "Normal" install. Make sure you hit custom and see what else it will stick you with or give you the option to avoid.