I only have about 40% free Space left on my 500 GB Hard Drive (198 free space and 302 used). Will this slow down my internet and computer speed? I'm thinking of adding a portable hard drive and transfer my large media files there if it will make my speed faster. If only having 40% free Hard Drive Space left will not slow down my speed, what percentage will: 30%, 25%, 20%? Thank you for your input.