However, if you try build another blueprint (just say you restricted that supply of concrete to free up some robots), there will be no movement for a minute or two, before everything then kicks into action. All the construction robots are marked as 'available' and it's pretty confusing as to why nothing is happening.
I know it'll be something to do with the optimisation in a way that you won't notice most of the time, but the delay becomes very obvious when 99% of the jobs are all 'missing item' ones. I think newer blueprints should get priority anyway (maybe find the nearest robot not carrying anything and reassign them for each item), which would possibly also solve this problem

I can attach the save if needed, but I'm guessing it's a general thing.



 That'd possibly be checked every few seconds to leave processing power for the things that actually need building.
  That'd possibly be checked every few seconds to leave processing power for the things that actually need building.