when i mention the slowness of the message mechanism this is both by design of Objective-C (for runtime features) and very measurable. this is why, for example, NSArray becomes prohibitively slow when you want to iterate across 1000s of members.

Objective-C is nice, but its slow by design, and this rules it out in a concrete way for a lot of the work I've done.

Its sad when optimisation comes down to 'knowing better than the compiler' only because of language constraints. (even C has this problem with struct layout for example - its just prevalent when using Objective-C/Cocoa (Touch))