the.com/bottleneck
The one slow part deciding how fast everything else gets to be.
means A single point in a process or system that limits the speed or capacity of the whole thing.
from From the literal neck of a bottle, where the wide body funnels into a narrow opening — pour fast and the glass throat throttles the flow, no matter how much wine waits behind it.
Fish factGenetic bottlenecks shrink a species' diversity drastically
Traffic truthOne merged lane can stall miles of cars
CounterintuitiveRemoving a bottleneck just reveals the next one