in comparisons i did several years ago, MIPSPRO was definitely faster, but compared to not having an executable at all, gcc is acceptable. most of the work in getting the MIPSPRO version working at that time was dealing with the issues that blender was written assuming gcc and GNU tools. which meant you had to keep all of those up to date too. now with nekoware it's easier - you may only have to deal with the lazy data typing gcc lets you get away with.
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