Benchmark: timing 5 iterations of sort, walk once manual insert, walk once with sort...
sort: 60 wallclock secs (60.37 usr +  0.02 sys = 60.39 CPU) @  0.08/s (n=5)
walk once manual insert:  3 wallclock secs ( 2.79 usr +  0.00 sys =  2.79 CPU) @  1.79/s (n=5)
walk once with sort:  3 wallclock secs ( 2.76 usr +  0.00 sys =  2.76 CPU) @  1.81/s (n=5)