It means that the pace of everything is measured by the speed, because its very lifeblood is the blaze of the boom.

This couplet speaks to the duality of existence. Mir Taqi Mir suggests that while everything in life—every change, every moment—may appear slow and gentle, there is an immense, vibrant energy pulsing beneath the surface. It's the secret lifeblood, the 'rehgiraai,' that gives true life its overwhelming 'dhoom.' It reminds us that true passion and intensity often hide behind a calm facade.