Hey Sean -- how frequently do you use the library on this x64 machine? Is it possible you've run Mixxx hundreds of times (with the same mixxxdb.sqlite)? If so then this is possibly a dupe of Bug #1054836 which only happens on 1.11 if you have hundreds of history playlists (a new one is created every time you run Mixxx).
Hey Sean -- how frequently do you use the library on this x64 machine? Is it possible you've run Mixxx hundreds of times (with the same mixxxdb.sqlite)? If so then this is possibly a dupe of Bug #1054836 which only happens on 1.11 if you have hundreds of history playlists (a new one is created every time you run Mixxx).