Optimisation means preparing a TIFF from a RAW file to expected industry standards, with a just-full dynamic range and qualities that a typical viewer would expect, and which appear normal. The qualities include overall brightness, contrast, colour saturation and sharpness. This is what, for example, a professional digital pre-press company would do to tweak images if necessary.
Over-processing and failure to process adequately are the two widespread ills of image editing, and optimisation involves a lot of avoidance – that is, not using adjustment sliders that superficially offer interesting effects. Optimisation ignores creative choices, and so is not necessarily a guaranteed way of processing. Rather, it’s a starting point. It means the overall colour balance is free of an obvious cast, with anything expected to be neutral (concrete, for example)…