And even if none of these stand, qx captures and saves the output in memory, thus it can eat too much memory unneccessarily if you discard the output.

Uhm, no. Testing seems to indicate qx// is context aware, and doesn't store anything in void context. Running:

perl -wle '`perl -le "print q!*! x 1_000_000 while 1"`'
[download]

doesn't consume much memory, but running

perl -wle '$_ = `perl -le "print q!*! x 1_000_000 while 1"`'
[download]

quickly consumes all memory available.

Abigail