On 23 Feb, Nick Lamb wrote:

>>  Does this mean that you agree to ditching all the special code
>>  for the 3 and 1 byte case as well? I'd really love to see this
>>  changes although as already stated this might introduce a bit 
>>  memory overhead in case the user didn't use the alpha channel
>>  at all.
> If we can get back COW during 1.3 this overhead is zero (all new
> channels / layers etc. can be created as COW tiles with the
> apppropriate contents -- huge speedup).

 COW is indeed a good thing. However I assume you address the mentioned
 memory overhead with your answer and I'm not sure how you would avoid
 it with copy-on-write. The 3 byte will be always problematic because 
 we always step over memory boundaries which is a huge loss in
 performance on any modern architecture. However restructuring the code
 to have a special function for each of the possible cases could be a
 cure to the branchprediction smashing distinguish in the source of the
 performance critical functions.  



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