I have to disagree with the OP. It seems like with my system, the new AA.com is actually faster and has fewer timeouts or lockups than the oldAA.com. Although I have yet to book on the new AA.com, I have repeatedly checked planned trips and particularly like the "Modify Search" box that allows you to change dates, passengers, and even cities quickly.
I applaud the new AA.com as an improvement over the old version.