I'd recommend switching keyboards. You can download the stock google keyboard from the playstore, it feels way more snappy than the Xperia keyboard. (If it doesn't show up for you, it's because the app is region restricted, look here for details and download: http://www.androidpolice.com/2013/06/05/new-app-google-adds-stock-android-keyboard-to-google-play-for-all-4-0-devices/ ) Edit: I switched because I was used to Google's keyboard and I ran into lag problems with stock Xperia keyboard when I used spellcheck/autocorrect for two languages. It's not a good fix if you like the Xperia keyboard, but you could at least try if it is faster for you.
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