In the past we've had it where where each bot is allowed a certain amount of "computation", with different upgrades giving you more "computation" each turn.

Machine-independent isn't really the write word, more of that we want the same two bots fighting on the same maps to be deterministic regardless of the machine its being run on.

For mechanics like this, we've found that bytecode instruction counts are the best metric we currently have, since anything that is time-based could result in different results depending how the CPU schedules the bots, and doing something like using PIN or another system to count assembly instructions turns it into a competition of who can write the most optimized assembly code.