> understanding was that GPUs are especially efficient at rendering from textures, while being relatively slow at bit twiddling.
That understanding is very out of date. For GPU's made in the last 15 or so years a texture lookup is roughly 100 times as slow as a bitwise operation.
That understanding is very out of date. For GPU's made in the last 15 or so years a texture lookup is roughly 100 times as slow as a bitwise operation.