UseFastQuads

useFastQuads is both a global property (the useFastQuads), and a optional property for the copyPixels command:

vOptions = [#useFastQuads: TRUE]
vTarget.copyPixels(vSource, vTargetQuad, vSourceRect, vOptions)

If useFastQuads is set to TRUE, quads whose opposite sides are not parallel and which do contain a solid color may not appear at their best. This case is fairly rare; setting useFastQuads to FALSE decreases performance. In most case setting useFastQuads to TRUE is the best option.

Skewed sprites and rotated sprites will appear fine with 'the useFastQuads' set to TRUE. You only really need to set 'the useFastQuads' to FALSE if you are distorting your sprites or your copyPixel areas into kite shapes or arbitrary quadrilaterals.