Can you learn another language in the time it takes for your machine to boot? Do you turn on your PC when you go to bed, so it´s finished booting by the time you get home from work the next day?
When Windows loads its Startup file, it attempts to load every program in there at the same time. Therefore, if you have quite a lot of programs starting when Windows starts, each program will try and grab CPU time so that it can load.
If each program tries to do this at the same time, you soon notice the slow down that occurs, due to your CPU trying to help all the programs to load, and your hard disk accessing multiple files.
Startup Delayer allows you to setup how many seconds after Windows has started, to load each program.
If you have your mail program and a special clock starting up, then you can make your mail start say 10 seconds after Windows has loaded, and then the special clock start 20 seconds after Windows Starts.