The load on our database server has been growing over the last few days causing slow downs. Since our overall traffic is not going up right now, this suggests that our last update caused some performance issues.
In order to analyze our traffic, I will be doing some performance tuning and query logging to attempt to get to the bottom of this problem. To that affect, MusicBrainz will have a couple of short downtimes today as I tinker with our database server.
Sorry for the inconvenience.
MetaBrainz Blog 
What kind of traffic isn’t going up? If it’s just unique hits, then maybe the slowness is partially because with the new update modders have a lot more to do (adding labels and release info).
Noa:
http://stats.musicbrainz.org/webstats/lingling/www.musicbrainz.org/
Overall daily avg traffic to the site is less than last month. Which makes no sense unless the DB server is running sub optimally. At least that’s my best guess right now.