A method of operating a tile-based graphics processor that executes a graphics processing pipeline is disclosed. When there are no more primitives left to be provided for processing to the pipeline for a rendering tile, it is determined whether any remaining processing steps for the rendering tile can be omitted, e.g. because they will not affect a buffer that will be output when the rendering tile is complete. When it is determined that a processing step can be omitted, that processing step is omitted.