Maxthon is finally back on track with this release. It seems to fix the new tab/freeze/crash issue that I was having, even with multi-threading on.
Memory usage seems better, too.
Firefox 3, 1 tab open (google.com): 60MB
Maxthon2, 6 tabs open (last.fm, facebook.com, gmail.com, myspace.com, maxthon forum [duh], drupal.org): 50MB!