https://play.rust-lang.org/?version=stable&mode=release&edition=2021&gist=41e1df59aeafe6f45fccaa192941d6d1

iter1とiter2は>>295からの引用
Ryzen 7 3700Xで計測
ジェネリクスへのこだわりを捨てればこのくらいは速くできるよ

fib_iter1               time:   [7.2754 ms 7.2824 ms 7.2907 ms]
Found 2 outliers among 100 measurements (2.00%)
  1 (1.00%) high mild
  1 (1.00%) high severe

fib_iter2               time:   [7.8536 ms 7.8678 ms 7.8818 ms]

fib_biguint             time:   [4.9757 ms 4.9784 ms 4.9812 ms]
Found 5 outliers among 100 measurements (5.00%)
  5 (5.00%) high mild

Playgroundでもベンチマークできればいいのになあ