I have been to Louvre many many times. I always go in june, july , august and sometimes sept. I have never waited more then 5-10 minutes and that was to get through security. The trick is simple. Do not enter Louvre via the Pyramide.. every runs there. Enter via the Caroseul Mall entrance off Rue Du Rivoli. You can buy ticket from machines or you can buy them from the Tabac in the mall. Last time I waited 2 mintues for lady in front of me to pay for her postcards.. then bought my tickets and walked out to musuem where there was only maybe 10 people in the security line. We saw the line up at the Pyramid entrance ,, it ran across the square.. wow,, these people need to read travel forums! lol
The Orsay one can avoid long lines even in summer by buying ticket the BEFORE the day of your visit .. there is a window kiosk just to the left of the main entrance you can purchase a ticket there good for ANY day but day of purchase. OR .. you can arrive early. I suspect in Feb you will need to do neither of those things.