Yes, there is a Guinness World Record for speed texting. And the current record holder just set the bar much higher for himself with a new record, accomplished with Apple's iPhone 6 Plus.
Marcel Fernandes Filho, a 17-year-old from Brazil, set the Guinness World Record for "Fastest Time To Type A Text Message On A Touchscreen Device" back in May with Samsung's Galaxy S4 smartphone. He achieved the feat with the customizable Fleksy keyboard.
That's pretty fast.
You can download Fleksy for iOS or Android here.