If it is the photopost integration with ubbthreads then for sure not the cause since its footprint is concentrated on including a stylesheet and allowing the users that check the gallery to use the same login.
Try to have a look whether you installed any modifications that enrich the information on the post screens (showflat or showthreaded). That usually has a huge impact on the database as well.
What I also saw is that when I look at one of your posts the debug information changes to :
Generated in 0.699 seconds in which 0.659 seconds were spent on a total of 31 queries
which is roughly the same amount of queries but 3 seconds faster. The solution must be in the IIP I think. Try deactivating all the pal boxes and refresh the cache. Then reload the page with only 2 or 3 boxes and keep some statistics. Tweaking the pal boxes that appear will definitely help. Finally try reducing the newspal display boxes (say make it 2 or 3)
