The ubershader is the thing that emulates Flipper at a low enough level to use the precompiled "shaders" directly. Prior to that the precompiled "shaders" were

The ubershader is the thing that emulates Flipper at a low enough level to use the precompiled "shaders" directly. Prior to that the precompiled "shaders" were examined and recompiled into individual shaders, a process that took time. (Why "shaders" in quotes? Because they weren't shaders as we know them today but really more like lists of hardware flags for how to flow data through a fixed function pipeline)