Hello,

For a better game flow I would suggest to change the production of buildings after you are able to have upgraded the Belts and Furnaces. It makes no sense for example to upgrade them already to 30/min or 60/min when a belt is not supporting it really.
In Short: Reorganizing the Tech Tree to be able to first "easy" upgrade the belt speed and extractors (cost can be higher but previous tier) and then unlock with the new science the Production items to the higher amount of items as throughput and also already supported by the belt.
This would also avoid playing hours with Production buildings showing higher build speeds but you still need to build for lower for example.

First upgrade Belt Speed, then the Extractors with current science and that followed by the Production Buildings with new science. Either way is a bit poisoned but think that would follow a better flow.

Thank you for that awesome game!!!