Here's the link, for those interested:
https://techreport.com/review/how-atis-drivers-optimize-quak...
Personally, I don't believe this is a good example; as this was ATI purposefully crippling the experience (downscaling textures, being the prime aspect) to cheat benchmarks. OP is more referring to "transparent" optimizations (the same experience, but made to run faster for the GPUs architecture, usually via operation reordering or shader modifications).