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.