This happens to me CONSTANTLY with Safari, Facebook and Twitter. So irritating. Could it have something to do with the fact that I have a 2 year old 4S or that I'm still running 5.01?
Is programmed obsolescence man. The will make Safari to run crabby on an 4/s to compell u to shell$ out for new hardware. Try the Atomic browser (free), runs smoother than Safari, I like it.
It's more iOS7 than anything. My iPhone has crashed more in the past few months with iOS 7 than any of my iPhones ever did combined since 2008.
The OP is still running iOS 5.0.1, they shouldn't have any issues with Safari that weren't present before.
Plus the 4s is still a pretty decent piece of hardware.
I am on 4s/6.1.3 and Safari starts to feel a little sluggish. Pinch-zoom it and it takes a few seconds for it to come back, same when changing orientation.
One of the reasons why I went back to Android was because Apple's own first party apps were crashing on a daily basis.