My advice is to just turn it on and forget about it. It's not going to hurt anything. IIRC, the OS is responsible for implementing CoW for fork(), but Perl threads are a different matter, since it looks like a single process as far as the kernel is concerned.
"There is no shame in being self-taught, only in not trying to learn in the first place." -- Atrus, Myst: The Book of D'ni.