Great mod, but it uses an unexpectedly high amount of CPU time, where I would naively expect none is used.

For example, in my current game, it consistently uses 0.8ms per tick (for 8 big berthas on the map), more than any other of the 100+ mods I installed.

Yeah that’s true. I had to implement a custom power management algorithm.
But that should be the only source of lag. If you disable the power consumption in your mod settings it should use less CPU time.
However, I have a CPU time of 0.085ms for 12 Big Berthas. With 144 Big Berthas it consumes about 0.8ms on my PC.
Either my PC is ten times faster or it is something related to your savegame / mod selection.