Wordpress 3.3 dog slow when logged in - performance

Question

EDIT3
Boulevard theme was the culprit indeed. An update notifier service runs on every page request for logged in user (one would hope only for admins), which, for some reason takes #10 seconds of limbo-nothing-happening before page all of a sudden loads. This of course affects the logged in user in both admin and public facing screens. Removed the file and voila, snappy page loads all around.
rant: entire day wasted, loss & gain with 3rd party software, arggghhh ;-)
EDIT2
Not MySQL either, Boulevard theme seems to be the culprit. How to workaround, I am not sure. Client paid for the theme and wants to use it, but administering the site is a nightmare; i.e. waiting forever for admin screens to load...
EDIT
Ok, I confirmed that initial http request arrives instantly at the firewall, logged in or not. However, there is then a 10+ second lagtime before further activity occurs at the firewall layer. I assume that WP sends along the session cookie and then, for reasons TBD, there is a delay in verifying that remote user is logged in.
I'll check MySQL now, assumed with low cpu/memory usage that this would not be a resources issue, but maybe it's a slow query at play...
ORIGINAL
What is the deal here?
new to WP, performance is fine when not logged in; however, 10+ seconds to load public or admin screens otherwise.
linux top shows nothing spectacular happening (no spiked cpu, memory usage), so what exactly is WP doing during these 10 pointless seconds? arggghhh ;-)
ajax requests are snappy, so something is happening with normal synchronous http requests that is making WP dog slow (hard to get much done waiting for screens to load, worse than waiting for an application to compile, at least something useful is being done while you wait!)
My semi-workaround is to have Chrome browser window opened, not logged into WP. There are I can view public pages instantly. Then, in Firefox slog away playing the waiting game logged into admin panel ;-(
Clues appreciated, WP impresses (look & feel) but not so much in this respect, madness...

Answer 1

Some Wordpress plugin that implement a cache, turn off cache for a user who is logged in. Wordpress is also known for using a lot a memory. It can slow down the global performance of your web server.
You can monitor the memory used by Wordpress for each page, using Memory Viewer

Answer 2

UPDATE: I just found this piece of code in update-notifier.php
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_TIMEOUT, 1);
$cache = curl_exec($ch);
curl_close($ch);
TIMEOUT was set to 10 (I guess seconds), edited to 1 sec as above and now while logged in everything works fine...10 seconds is just to big value