Over a period of time computers perform lots of updates to keep security up to date and to fix software issues, this along with many hidden temporary files that are created whilst you use your computer can cause your machine to slow down dramatically.
Re installation of the operating system will provide the best repair, we can alternatively try and remove the hidden files and update files however this never gets near the faster end result of re installation.
For best results we can install a new Solid State Hard Disk Drive, this is more costly as we need to backup your old HDD as well as provide the hardware, however it will give your results of up to 6 times faster than when you first had the machine!