Windows 10 has random prolonged boot (Explorerinit phase)

I already posted my problem in other forum, but I didn't find any solution, so here we go:

So recently I got a Dell XPS 15 9550. I immediately re-formatted it and install everything from scratch. I'm also only using Local Account for my laptop. Now weirdly, I've been experiencing several occasions where the Windows will get stuck at the Logon period (the one with my useame) for as long as 30 seconds. I have no password btw. It happens randomly, every restart or cold boot.

I then installed the Windows Performance Toolkit to boottrace my Windows. Using the Windows Performance Recorder, I tried to record my laptop in 3 consecutive reboots. 2 reboots are actually only taking around 10-12 seconds. However, the 3rd reboot took around 40 ish seconds. When I looked at the trace, I found out that on the 3rd boot, the ExplorerInit phase took as long as 30 seconds. On the other 2 boots, it only took around 1.5-2 seconds.

Unfortunately I caot upload the .etl files, as each measures 1.2 GB....... I can only post some of the screenshots.

One of the fast boot times

The slow boot time

Any help / suggestion would be of great help. Thanks.

EDIT: Since I caot post a 3rd link, I managed to check the Processes, and it seems like there are 4 backgroundtaskhost services that took 20-30 seconds each to finish. Weirdly, on the other boottraces (the fast ones), not backgroundtaskhost services are found.