go task manager and then click the processes tab. Go through every one, google the name of each one and see if its necessary, unecessary or a virus. If its a legit program trace whats causing the bacground program to run, and fix it ( reg edit would be useful, but be careful). If there are virus file running slowing your pc down, try deleting each physical file. If it tells you no, delete them in safe mode. There is always something you can get rid of