Sorry - me not being clear. I meant the Random Access Memory (RAM) which runs the programs, and which is cleared completely on shutdown or restart, i.e. when there's no power on. RAM can get eaten up with continuous use, and the computer runs slower and slower - which is why I restart at least once a day, rather than leave the computer in, say, sleep mode.

I also understand that, at peak times, the broadband providers even out the supply among users in a certain area - which can mean slower speeds overall for everyone.