While tinkering with robot speed encountered following:

Ultracube warning: optimized cube control routines failed. This may be due to compatability issues with another mod, or a bug that should be reported.

List of mods: base 1.1.109, aai-loader 0.1.4, alien-biomes 0.6.8, flib 0.14.2, flow-config 1.0.7, Krastorio2Assets 1.2.3, Milestones 1.3.25, resource-highligher-dark 2.5.2, Ultracube 0.5.6

Context. Because this mod (for the reasons I don't understand) drains enerty from bots, I came up with the question "how much levels of working robot speed do I need to bypass this drain?". So I have setup with cube in the chest near to roboport and requesteer chest on the top edge of roboport coverage (that was the setup in which I learned about energy drain). The answer is somewhere between 110 and 150 levels (force-researched them through editor). But when bot (I was testing fast one) actually delivered cube to destination, I got message in question.