I have a suggestion for the readers who are seeing slow start ups after installing 10.3.7.
I recently got around to installing the 10.3.6 Combo update on my 15' TiPB. MUCH slower starting up, mostly after logging in. I remembered seeing a tip somewhere to clear the System and User caches. So I used my copy of Cocktail (but there are other utilities out there as well) to clear/delete the system and user caches. The user cache took several minutes to clear, BTW. Afterwards, the machine was even faster than before installing 10.3.6! So try it with the 10.3.7 update.
It's common to see recommendations to redo permissions after OS X updates. I've found deleting caches to be much more important, and occasionally deleting preference files. Neither is part of routine maintenance. OS X system updates ought to routinely delete all caches -- there's no reason not to start afresh.
I prefer ONYX to Cocktail. I think Cocktail's installation is too invasive, and it behaves oddly when one tries to install as a regular user (needs to be installed and run as a logged-in admin, not as a sudo'd admin, but it doesn't say that...).