Persistence paid off!

Your first rountine (the one with the three Filter and two Transpose calls) bounces between 0.02 and 0.03 seconds, mostly 0.02, so it matches the speed of my routine using only three active lines of code (eight lines of code less than mine)! Congratulations! I was a little surprised that those two Transpose calls did not slow things down more; actually, I would have thought the three nested Filter calls might have slowed thing down as well... obviously I would have been wrong. Again, well done. By the way, your other two attempts did not fair anywhere near as well... the second one taking about 0.14 seconds and the last on about 0.85 seconds. Oh, just for information sake, from the list of 10001 continent names, 2820 of them were being deleted.