You can always install a thread enabled version of perl in the non default location just for this script. Or you can fork like is staed above. The question is what platform and how many CPUs is this running on? If it is decompressing and compressing there may be a CPU bottleneck to begin with (hence it is slow) sor threading or forking on a system may make performance slow if the threads are fighting for time on the same cpu. force contex switches can play not-so-fun games with your speed. If you have enough cpus on the box then fork or thread, if not consider taking dws's advice and make a buisness case for more diskspace.