What can be useful in this case is analyzing the Windows startup procedure to identify if something is causing any problems. On a clean and trouble free system, the boot will be as fast as the hardware and Windows allows, if something is not quite right or loading improperly, the boot will slow down and it might even cause the computer to slow down after the boot has completed. Windows is a complicated operating system underneath and during startup most of the programs, drivers and services needed for the computer to function are loaded.
