Prior to 2.3 (the feature turned up in 2.3 according
this), text was selected by tapping and dragging your finger over text you wanted to select. It was completely unusable on touch screens, but I can't recall having problems with the browser crashing using it.
I don't have any proof that it is the cause, but as you said it just seem like the browser is most prone to crashing when position the caret or trying to select text to copy and paste.