Yep, Hosed is correct (as usual
). Basically the performance hit depends on:
(1) The natural orientation of the display
(2) The orientation of the image being copied to the display.
If you only use square areas the performance in landscape mode is 100% identical to "normal" mode. You can test this with the "simple" demo. If you use rectangular areas or the built-in system font (the system font will be optimized in the next version) the performance hit depends on how the image is aligned to the natural display orientation.
GapiDraw always translates all coordinates and even flips directions as much as possible to ensure that all data is copied in a cache-optimized way.