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I rewrote all my solutions in Rust (except for day 10 part 2) and these are the runtimes on my i7-3770 from 2013 (this measures CLOCK_PROCESS_CPUTIME_ID, not wallclock):

day01/1 [      00.000501311] Result: 1066
day01/2 [      00.000400298] Result: 6223
day02/1 [      00.000358848] Result: 12586854255
day02/2 [      00.000750711] Result: 17298174201
day03/1 [      00.000106537] Result: 17405
day03/2 [      00.000404632] Result: 171990312704598
day04/1 [      00.000257517] Result: 1626
day04/2 [      00.007495342] Result: 9173
day05/1 [      00.000237212] Result: 505
day05/2 [      00.000142731] Result: 344423158480189
day06/1 [      00.000229629] Result: 4076006202939
day06/2 [      00.000279552] Result: 7903168391557
day07/1 [      00.000204422] Result: 1622
day07/2 [      00.000283816] Result: 10357305916520
day08/1 [      00.029427421] Result: 84968
day08/2 [      00.028089859] Result: 8663467782
day09/1 [      00.000310304] Result: 4764078684
day09/2 [      00.015512554] Result: 1652344888
day10/1 [      00.000796663] Result: 375
day10/2 [      --.---------] Result: 15377 (Z3)
day11/1 [      00.000416804] Result: 753
day11/2 [      00.000660528] Result: 450854305019580
day12/1 [      00.000336081] Result: 577
day12/2 [      00.000000695] Result: no part 2

A little under 90 ms total.

On my Samsung NC10 netbook from 2011 with its Intel Atom N455 at 1.6 GHz:

day01/1 [      00.003771326] Result: 1066
day01/2 [      00.003267317] Result: 6223
day02/1 [      00.003902698] Result: 12586854255
day02/2 [      00.006659479] Result: 17298174201
day03/1 [      00.000747544] Result: 17405
day03/2 [      00.002737587] Result: 171990312704598
day04/1 [      00.001263892] Result: 1626
day04/2 [      00.044985301] Result: 9173
day05/1 [      00.001696761] Result: 505
day05/2 [      00.000978962] Result: 344423158480189
day06/1 [      00.001387660] Result: 4076006202939
day06/2 [      00.001734248] Result: 7903168391557
day07/1 [      00.001295528] Result: 1622
day07/2 [      00.001809659] Result: 10357305916520
day08/1 [      00.277251443] Result: 84968
day08/2 [      00.284359332] Result: 8663467782
day09/1 [      00.003152407] Result: 4764078684
day09/2 [      00.071123459] Result: 1652344888
day10/1 [      00.005279527] Result: 375
day10/2 [      --.---------] Result: 15377 (Z3)
day11/1 [      00.003273342] Result: 753
day11/2 [      00.005139719] Result: 450854305019580
day12/1 [      00.002857552] Result: 577
day12/2 [      00.000004421] Result: no part 2

A little over 700 ms total.

I like this. You get performance that’s more or less in the ballpark of C, but without the footguns.