The flow rate is tiny that is true, but that parameter determines how fast the pump recovers the vacuum. Every time a pick up occurs the pump has to swallow a bit of air. (The air inside the tubing from the solenoid to the nozzle.) The faster it does it, the faster the vacuum at the pick up nozzle reaches the maximum. I think the main issue with built-in pump is actually low flow rate. The max vac level is not that bad, I think it was like 560mmHg, and my big one reaches 670mmHg. So only 20% less holding power. But it is very (relatively) slow at recovering vacuum. Keep in mind that if it takes a second to recover, that's almost as long it takes for the part to travel from pick up to placement.