[thaumasiotes]

> You also have to consider the Amdahl's law: a 10x speedup on 10% of the project is just a 9% speedup overall.

It's a 10% speedup, unless you think that a 100% speedup would reduce completion time to zero rather than cutting it in half.

Assuming that "10% of the project" is measured by time requirements, when you get a 10x speedup on that part of the project, you'll end up completing 100 units of work in 91 (formerly 100) units of time. Your work rate is then 100 / 91 = 1.099 times what it was before; that's an improvement of 10%, not 9%.

(Sanity check: suppose you have a project that will take 100 days. That project is reassigned to someone 10% faster than you. They will take 100 / 1.1 = 90.91 days to finish.

If they were 9% faster, they'd take 100 / 1.09 = 91.74 days to finish.

Does a savings of 9 out of 100 days of work look more like the project that saves 9.09 days, or the one that saves 8.26 days?)