The texting application on my iPhone 4S iOS 6.0.1 is really really slow.

The texting application on my iPhone 4S iOS 6.0.1 is really really slow. Like when I'm in a different application and I get a text and I tap the banner it switches to the text application but takes like 15-30 seconds to load anything. It just sits at this screen. And also I have started to nitice that my phone hasn't been going off when I get a text, I'll be sitting there with the ringer on and I'll open my phone and there a text! Like why isn't going off?