I know it is kind of early to be reporting back but I want to give you a quick update. I've since changed keyboards from SwiftKey to Swipe. I had no problems composing any posts or replies on mobile Safari. It did not lock up or freeze. I was able to reply to several posts on the forums. I'm going to keep using mobile Safari for another day or two and see if anything happens.
Sent from my ancient but trustworthy iPhone 5.