Happy New Year, everyone!
I'm having the exact same issues with my 3Gs as described in many other posts in this forum. Apps take forever to launch, native apps like SMS, Mail, Phonebook, Camera, System Preferences etc. respond sluggish and the overall performance feels slow and sluggish in general. It's a 8GB iPhone 3Gs, and I had performance issues back with iOS4 as soon as it had less than 1GB of free space. I considered that to be annoying already, however, I didn't expect the problem to worsen with the upgrade. I actually had hoped that the performace might improve. Well, silly me — how could I've been so naive, huh?! I've deleted so many photos and music already, that I'm up to 1,9GB in free space out of 6,2GB capacity. I mean seriously, what the ****!
It's very clear, that this is not a sporadic problem, but that a majority of 3Gs users who are running iOS5 are having similar issues.
If apple is going to further refuse to address this, my next phone will be an android for sure. I'm not letting myself being forced into upgrading my hardware. APPL — fix this… quickly!
Cheers!