Avoid UTF8 processing if you don't need it and have extra speed Many often used utilities are much slower with UTF-8 processing. If you want extra speed and do not need UTF-8 processing, disable it using export LANG=C export LC_ALL=C (not needed if LC_ALL was not set) compare time grep -i -c some_string some_large files with LANG=en_US.UTF-8 and same with LANG=C On modern CPU grepping like this a 100MB files take some 2 seconds with UTF8 (Celeron 3GHz) and is about hundred times faster (0.02s) with LANG=C Even more spectacular speedup is for sort -f