English to Czech Other Media / Multimedia management, business systems

Originally I suggested "zúžení" but it did not make much sense. Otherwise, also "lead-time" occurs in this sentence, which I don´t understand much here too.

Taken from sentence:
Then we must make sure that it´s always the most expensive investment in the process that is the bottleneck, and allow the bottleneck to govern the flow of materials. So we mustn´t put more materials into the flow than the bottleneck can cope with, becuase otherwise we get unnecessary intermediate stock-up stream of the bottleneck as well as long lead-times.