A quick Profiling on a 1v1 has show that carry capacity techs can actually lead to serious lag spikes.
The problem is that they change 4 carry capacity modifiers, and the modifiersManager is currently not clever enough to batch these changes, so it Broadcasts 4 times.
Units will then recompute their gather rates 4 times, and since most units are affected, this can be quite slow.
In the attached replay, it takes ~90ms on turn 2658. I have no doubt that with more players, it would become unacceptably slow.
By doing slightly less work, we can bring this down to about 25ms, which is a much more acceptable lag spike, even with 4x the units.