Hello, I solved this problem and I would like share the solution in the forum.
Either using xfce or gnome, the DE took about 15 seconds delay to show up. I found that was a problem related to Jack audio server (qjackctl) that I need as a startup application.
The solution was the following command:
sudo apt-get -y remove --purge qt-at-spi
that reinstall qt-at-spi so jack doesn't waste time "looking" for that