It should take about 30-40 seconds from "bong" to desktop, minus log in time and no starup programs.
Lion has a annoying feature that loads the last programs used, you need to disable this.
You obviously upgraded Lion over Snow Leopard, Snow Leopard is faster on the same hardware than Lion.
A fresh install will speed things up quite a bit.
If you backup your user data folders off the machine (to a storage drive, not TimeMachine) disconnect,
c boot off the 10.6 disk, erase the entire drive (use the Zero option) install, (use the same username)
update to 10.6.8 and then upgrade to 10.7 (hold option key and click on Purchases to redownload),
update, then install Lion compatible programs,
then your files manually from backup (not a migration or TM restore)
in that exact order, you should have the fast configuration and a clean system
After that if you Carbon Copy Cloner the entire Lion OS X partition (no need to do the Lion Recovery Partition for this) to a blank external powered drive, then option key boot from it and erase and reverse clone OS X Lion back onto the internal OS X Lion Partition, that would do wonders to further optimize the running of Applicaitons as they all would be written to the "hot band" of the hard drive.
Another tactic is to keep one's boot drive below 50% filled, as the later 50% always results in slower read/write times, so anything written there is going to be slower. Everything needs to be on the top 50%, which the clone and reverse clone technique will achieve.
So your steps are as follows, backup, fresh install, install programs, then users files (but dont' go over 50% of the drive) clone this pristine system (for bootable backup) then erase and reverse clone. Disable any and all startup programs.
This should give you the best you can extract from your hardware.
Got to remember, Apple has a need to create hardware turnover, so they do indeed feature bloat OS X to slow down hardware.
I've installed Linux on 10 year old PC's that act much faster than even some new Mac's, the size and complexity of the operating system relative to the hardware it's installed on also comes into play.