This could probably be optimised when pp_av2arylen is called in rvalue context.

Done by commits 02d85cc37a4acecafdc2f0b45640b03cd1f4ac71 and 28c5b5bcd7f52e6b2219508a1066cd0ccc8dd19a. You'll see these changes in 5.11.2 (next month's dev release) and 5.12 (early to mid 2010)