Applications launch slowly the first time, but...

Question

Okay, not sure why this happens and I've been wondering about this for a LONG LONG time, but why is it that applications seem to take forever to launch the first time you launch them after booting up? If you quit the app and at some point relaunch it, then it almost opens instantly. However, if you shut down or restart the computer at some point and then launch the app again, it takes ages to launch again, but only the first time. This behaviour happens with both Apple and third party software.
I have checked all the usual suspects: hard drive space (only 52% used), hard drive hardware (passes diagnostic scanning), RAM (I have 8GB), desktop (it's not cluttered and contains no folders), disk permissions (verified and repaired), software (always updated with latest versions), widgets (don't have many installed), wallpapers (never use animated wallpapers), login items (hardly any), PRAM & SMC (I've reset these). So, basically, I think I've done everything except reformat the drive and reinstall OS X.
My system specs are as follows:
  Model Name: MacBook Pro
  Model Identifier: MacBookPro5,1
  Processor Name: Intel Core 2 Duo
  Processor Speed: 2.53 GHz
  Number Of Processors: 1
  Total Number Of Cores: 2
  L2 Cache: 6 MB
  Memory: 8 GB
  Bus Speed: 1.07 GHz
  Boot ROM Version: MBP51.007E.B06
  SMC Version (system): 1.33f8
  Macintosh HD  Capacity: 999.86 GB (999,860,912,128 bytes)
  Macintosh HD  Available: 472.71 GB (472,705,077,248 bytes)
So, as far as I can tell, I've got no explanation for this behaviour. It's very frustrating/annoying - but not enough for me to want to do a whole format/reinstall.
Any suggestions anyone? If not for a solution, what about an explanation as to what's happening?
Thanks!
Joe.

Answer 1

To understand the why of this relative slowliness, you must understand that no application is really self-contained, or standalone, whatever the OS. All applications rely on so-called native code to function. Basically, some libraries (graphics, mainly, but not only) that are already installed on your machine, as part of the system, or installed by some third-party software.
On a cold boot, all this needed code has to be launched and installed in memory (physical and/or virtual) before the application core can be launched too. In your case, maybe some preference files are corrupted somewhat, or permissions need repair. You can try the following experiment: create a new standard account, give it admin rights, log in this new account and check how long it takes for your usual applications to launch. If they're quicker, then there's a problem with your main account; if it takes them the same amount of time to launch than in your other account, then you might consider adding some RAM on your machine, or free some space on your hard drive.
Or both. Preferably both...