AirBreather

If shaders don’t get preprocessed, then a lot of the same work has to happen later, it just shows up as a seemingly random frame that takes particularly long to render.

(edit to add:) or a section where some of the rendering doesn’t look quite right initially, if they do asynchronous rendering.

In the limit, the sum of all these delays can add up to the same amount of time that the preprocessing WOULD have taken, but you also don’t necessarily use every shader every time you play every game, so YMMV.