Windows 10 has been pretty shittacular for me so far on my laptop.
- Absurdly long startup time, have to wait on a blank screen for a couple of minutes after turning it on.
Really disappointed so far might give it a complete clean install and see if that helps.
When I started using the preview a few months back I had this for 3-4 boots then it vastly improved. I think it is doing Windows updates/Drivers installs but has no display to tell you what it is doing. I've also had it do this then restart and boot quickly. I thought it was quirk with the preview but maybe it is an issue with the retail release as well.
See how it goes after a few days.