lol.
i myself own a 32GB 3Gs + 64GB 4S. and recently using an Android phone for the work number. kind of grew on me, fastness, live wallpaper, widgets.
but android to me is more for technical people, at start is a bit going about if you come from an Apple device,but it's all good, don't need to know all aspect.
i wouldn't recommend Android if you like to use simple stuff.
lucky i haven't update the 3Gs to ios 5, but i however did save the SHSH blobs just in case apple new iOS is laggy like how iOS 4 with 3G
anyhow, i suspect it happen on minority of the 3Gs user or not as many for Apple to Care 😀
short term fix for now is to shutdown all apps. otherwise disable multitask, turn off all spotlight search use only application, turn off iCloud, and i think you should be OK.