I have a ssd boot drive too so I am very aware of any slowdowns in boot time, particularly for some reason when I see the booting "pinwheel" taking more revolutions than it usually does. In my case the average number of revolutions is about 3 (and I think it's about one revolution per second). So this weekend, when I installed the drivers for a Sonnet E2P eSata card I just got from OWC (and coincidentally as a replacement for a NewerTech MaxPower 6G PCIe card I returned) I was not happy about a 4x slowdown (12 revolutions of the "pinwheel").
I removed the installation and was surprised that I continued to have the longer boot time. I also had removed the card too. This got me curious. To make a long(er) story short, after some experimentation, I discovered that simply the process of installing the kext was the cause of my slowdown. It's related to how the system caches kext's.
It's interesting that the Sonnet installer tried to address the kext installation's cache effect in their installer (in the preflight script which is part of the package installer) but the instruction to handle it was commented out. And there is no such attempt in the MaxPower 6G installer (I saved the installer for some reason).
So all of the above was just to give the context of how I cured my boot time problem (I got my 3-revolution "pinwheel" again) and a possible suggestion on how to remove the slowdown after installing these eSata drivers.
In Terminal execute the following command:
sudo kextcache -e
You will get a prompt for the administrator password (from sudo) and the kextcache -e will start executing. This command may take a minute or two (I'm guessing that's why it was removed from the E2P installer) and a few messages may be displayed.
Next reboot. This reboot will take longer and that is expected since the kext caches are being fixed (rebuilt I think).
All following reboots should now be "normal" and hopefully back to your original boot speed (in my case the 3-revolution "pinwheel").
Now I am not saying this is guaranteed to address the boot slowdowns mentioned in this thread. I'm only describing my situation. But it can't hurt to give it a try. And if anyone does please report back whether it fixed the problem.