Comment by gene-h

Fluidics can work much faster upto 10 KHz[0], maybe even up to 30 KHz or higher if one uses light gases like hydrogen or helium. Although fluidic elements tend to be pretty and have a foot print on the order about a square centimeter. They are also difficult to scale down because it's difficult to maintain the same reynolds number.

Mechanical logic is an interesting option as some newly developed MEMS logic gates might be able to operate at MHz frequencies[1].

[0]https://apps.dtic.mil/dtic/tr/fulltext/u2/a084924.pdf [1]https://www.nature.com/articles/s41467-019-08678-0