Longer time to load windows?

Since I got my new computer back in November everything loaded extremely quickly, including windows with a rough estimate of 2 seconds of that screen where the orbs form the windows logo. Ever since last week the time to load windows has increased to a range within 15-20 seconds and I'm not entirely sure why. If anyone could shed some light on what's happening it would be greatly appreciated.

 Spoiler

posting that just in case it matters although I haven't changed anything since I got the computer