With super small dataset sizes like that it'll fit in the L2 cache and can behave differently. I did test this though, and for 20,000 items generated with your

With super small dataset sizes like that it'll fit in the L2 cache and can behave differently. I did test this though, and for 20,000 items generated with your loop: sort | uniq -c takes .017s (fastest out of a few runs) the awk command I used above takes .013s A trivial implementation I have in go takes .08s Additionally, using this 'protos' file which is 1,000,000 lines of tcp,udp,icmp: $ time (sort protos|uniq -c) 5915 icmp 332003 tcp 662082 udp real 0m0.232s user 0m0.739s sys 0m0.100s $ # fixed to count 'lines' and not the first column, which makes it faster. $ time awk '{lines[$0]++} END {for (l in lines) printf("%s %d\n", l, lines[l])}' < protos icmp 5915 udp 662082 tcp 332003 real 0m0.194s user 0m0.190s sys 0m0.004s $ time ./c < protos 662082 udp 332003 tcp 5915 icmp real 0m0.088s user 0m0.084s sys 0m0.005s so yes, I do test my assumptions.