Android shuffling letters in input

When I've typed more than a few lines in any text box, Android starts shuffling letters around. I'm on an S4. I've googled for this problem and found some indications that others might experience it too, but no bug report of any sort. So my question is if anyone else here has this problem?

I'll keep on typing to demonstrate the problem, it is bound to happen once this text grows large enough.

After a while spontanious scroll events start happening and the cursor starts bouncing around. Before you know it Android has made some inexplicable shuffling of your text and you go mad.

It is also posspossiblet the problem has somesomethingdo with the total amount of back-navigation which is perfperformed the total number of line breaks in the text.

Going back to edit old text seems to trigger the problem as well. I went back to edit the last paragraph and it happened! Reproduction sucess!