uniqmergesort mergesort
52.6s (~1e6)  54.1s (1e6)
44.9s (~1e5)  49.2s
37.8s (10k)   48.1s (third line, described below)
30.3s (1k)    47.0s
23.4s (100)   42.1s
16.5s (10)    40.4s
11.1s (1)     37.5s