In %hash || $foo, the %hash is in scalar context, so it has to iterate through the buckets to produce statistics on bucket usage. If the || is in void context, the value returned by hash is only ever used as a boolean (as || doesn’t have to return it). We already opti- mise it by adding a boolkeys op when it is known at compile time that || will be in void context. In sub { %hash || $foo } it is not known at compile time that it will be in void context, so it wasn’t optimised. This commit optimises it by flagging the %hash at compile time as being possibly in ‘true boolean’ context. When that flag is set, the rv2hv and padhv ops call block_gimme() to see whether || is in void context. This speeds things up signficantly. Here is what I got after optimis- ing rv2hv but before doing padhv: $ time ./miniperl -e '%hash = 1..10000; sub { %hash || 1 }->() for 1..100000' real 0m0.179s user 0m0.101s sys 0m0.005s $ time ./miniperl -e 'my %hash = 1..10000; sub { %hash || 1 }->() for 1..100000' real 0m5.446s user 0m2.419s sys 0m0.015s (That example is slightly misleading because of the closure, but the closure version takes 1 sec. when optimised.)