Solid rectangles are now rendered by the graphics card, instead of by the CPU. This is the first hardware accelerated operation implemented in the RadeonHD driver (for Amiga OS 4.x). The increase in speed can be seen in benchmarks made using the P96Speed utility (specifically, the RectFill() benchmark):

Hardware acceleration for R5xx cards is still a work in progress. In the meantime I have discovered how to switch the card to performing byte-swapping in order to convert from big-endian to little-endian modes for R5xx cards (Radeon X1000 series). Previously, all modes were simply defined as being little-endian, thus byte-swapping had to be performed in software by Picasso96. This is now handled automatically by the R5xx chipset.