In safe mode click on the start menu and type msconfig, then enter.
Select Diagnostic mode.
All AV and other services and startup programs will be disabled when you boot into normal mode.
You may then reenter msconfig and selectively check items you want to boot under the Services tab and under the startup tab. This will allow you to determine the program causing it, you may then uninstall it.
NOTE: your computer may not work as you expect if you have certain services disabled under msconfig, so if you have issues you may have something disabled that your computer needs!
I had the exact same problem as OP (Fast safe mode, slow normal login), but the other answers didn’t fix my issue.
In fact, it was caused by Windows Driver Profiler
Start Menu > Search > verifier.exe. Indeed, I activated it a few days ago because of several BSOD caused by failing drivers, and forgot to disable it. Once I disabled it (“delete previous config” option), everything was restored back to normal.
I guess that the same goes for other kinds of system-wide profilers, such as Windows Boot Profiler and so on.
So if the other answers did not fix your issue, you should check whether you still have a profiler activated somewhere.
You should be able to run the uninstall from safemode. How ever this may not resolve the problem. I would recommend running http://www.malwarebytes.org/ to do a full scan of your system and remove any other programs that may be running in the background. You may also run msconfig from the run command box, then look at the startup tab, remove any programs that you are sure you donw need. http://www.netsquirrel.com/msconfig/index.html. Windows safe mode only runs with the minimum programs needed to start windows which makes it super quick.
Let me know how it goes.