Once you get all that junk removed off your drive from doing all the previous suggestions, you’ll want to defragment your hard drive. Basically, this refers to re-organizing all the data on your hard drive so it makes it easier for the computer to find what it needs. Think about your hard drive as a warehouse full of shelves and pallets of stuff. If you went through the warehouse and got rid of 1/3 of the pallets of stuff, wouldn’t it be much more efficient to re-organize the pallets closer together and get rid of the empty shelf space? Sure would make driving around that warehouse to get to your stuff much faster!