> Size as a proxy for run-time frame rate simply doesn't work. You can make a tiny > build of MAME containing only the portions used for Donkey Kong or whatever, and it > will run at exactly the same frame rate as the full-size real deal. Algorithms trump > implementation details, and size is very much an implementation detail.
I think that when the word 'bloat' is used to often doesn't imply just an increase in size (as in size on disk or size in memory). I think it often means the 'bloat' of slower code that comes from advanced language features like virtual methods, multiple layers of interface, descriptive instead of optimized data structures, etc. That stuff does impact performance and I think it's what most people are concerned with when they talk about bloat.
I've meantioned this before, but I did some fairly thorough benchmarking of MAME 0.137 and then used the same benchmarking for MAME 0.141u3 and did notice a roughly 8% frame rate decrease across the board. References: