I've been using another AV product for quite some years, but as I am not entirely satisfied, I wanted to try Bitdefender AntiVirus Plus. So, I did uninstall my previous anti-virus software, plus I used the removal tool to remove any leftovers. Then I installed Bitdefender AntiVirus Plus 2016. After rebooting I noticed that Windows 10 Pro x64 had a big delay on the welcome screen. Researched a while, and found someone with a similar problem, saying to disable the scan at boot feature, which I did. This time, it did not delayed on the welcome screen, but had a black screen before, for the same amount of time. So, with the early scan enabled or disabled, it takes alot of time to boot, I have a very fast SSD. Removing Bitdefender and returning to my previous AV, works perfectly.