That's not Minetest. That's just on game running on the Minetest engine. There are tons of games and mods. The Minetest development team doesn't necessarily make mods.
That and another one. Minetest game itself probably has it too but I don't remember. You should have a pretty underpowered machine for it to be very noticeable and annoying.
I believe it is the implementation of the tick system in Mesecons (which VoxeLibre redstone is based on) that is the issue, and I agree it makes it nearly useless. It is absolutely an issue with the mod, not the engine, but would probably require a big rewrite of the mod to fix (not that I'm familiar with the actual implementation of mesecons).