Ars: Apple looking into slow iOS 4 performance on iPhone 3G
And as soon as you plug either device into iTunes, if it doesn’t already have iOS 4, it prompts you to update to this OS that dramatically reduces performance of already-slow hardware
I would not describe the reduction in performance as 'dramatic'. Worse, yes, but not dramatic. It is still a great device.
(Reblogged from Marco Arment)