The target time (in ms) to spend precompiling each frame when compiling takes priority or 0.0 to disable. When precompiling is faster the batch size will grow and when slower will shrink to attempt to occupy the full amount. Defaults to 16.0 (max. ms per-frame of precompilation).
Usage
r.ShaderPipelineCache.BatchTime [value]
Set via the console (~) or in DefaultEngine.ini / DefaultGame.ini.