Benchmark: timing 5 iterations of sort, walk once manual insert, walk once with sort...
sort: 170 wallclock secs (169.96 usr +  0.03 sys = 169.99 CPU) @  0.03/s (n=5)
walk once manual insert:  7 wallclock secs ( 6.90 usr +  0.03 sys =  6.93 CPU) @  0.72/s (n=5)
walk once with sort:  7 wallclock secs ( 6.86 usr +  0.00 sys =  6.86 CPU) @  0.73/s (n=5)