Paris museum pass and lines

No, the Museum Pass does not allow one to go to the front of the security line, which usually moves pretty fast. However, some guided tours may go to the front of the line, though some places have special entrances for tours.

Right. The pass allowed us to skip ticket lines but not "go to the front of" security queues. Also, the Towers of Notre Dame has no priority entry for pass holders, and at Saint-Chapelle you'll queue up with everyone else for a security check before bypassing the ticket line. From the Museum Pass website:

Sainte-Chapelle:
"Please note : the pass does not allow you to pass without queuing to Boulevard du Palais check-point. But it is not necessary to queue at the ticket office of the monument."

Towers of Notre Dame:
"Please note : For security reasons, there is no privileged access with the pass."

Other museums may or may not have separate entry/security lines for pass holders.

We were in Paris several weeks ago. We did not buy the museum pass; I price it out, and it never is a good deal for us. But I do buy tickets online in advance, which is getting easier and easier. At both the Louvre and Musee d'Orsay, they had a separate line for ticket holders. At the Louvre, at the pyramid entrance (we had to use this entrance because we had tickets for the special exhibits), we didn't really jump to the front of the line: our short ticket-holders line merged into the line with the non-ticket-holders to get through security. At musee d'orsay, the non-ticket holders get into the line for security and tickets that enters through the left side of the building; the ticket holders take the line and security point that enters through the right side. In each case, definitely a time-saver.

Most but not all sites have separate security entrance or lines for pass holders. You save big time at the Orsay and to a lesser extend at the Louvre, Pompidou, Orangerie

Thanks to all for confirming.

Sometimes there is a security line for people who already have tickets/passes and another near the ticket window. At the Louvre they had three security lines pass holders, people who bought tickets online, and next to the ticket line.

I got to the Louvre early and was first in the pass line. I didn't have a bag so they waved me through security. Since I was in earlier than most, I decided to go straight to the Mona Lisa. A Canadian couple who were first in the online tickets line caught up with me and we had the room to ourselves for at least five or ten minutes before anyone else showed up. My facebook photo of me alone with the Mona Lisa drew a lot of comments from my friends who had only seen her through a crowd.