Problem: repeatedly copying (relatively large) sections of text quickly makes the app sluggish until it has to be killed. (Thanks John Blommers for the report.)
When I instrument with prints, the sluggishness seems to happen in random draw() calls many times after I perform the copy.
I don't know for sure, but I'm initially checking if the cause is garbage generated by repeated string concatenation.
This attempt doesn't seem to make any difference.
O7QH4N4WVIN644DOEQ3OKCVGKPRAV3QUBAAO3L7XDXTK6TIRGCCQC