We encounter this problem a lot: the extremely popular and oft-used Admin Menu module causes performance problems.
Here is an example from a site we recently did a Drupal performance assessment for.
Executed 3,169 queries in 584.11 milliseconds. Page execution time was 4,330.86 ms.
As you can see, the number of queries per request is horrendous, and the site is a resource hog if left in that state.