I haven't seen any "tagmap" commits on the SVN for snes.c yet, but I'm pretty sure that someone will get to it soon since it's a high-profile driver. It's possible that one of the other developers has it "locked" due to some other uncommitted changes. By the time version 0.149 rolls around, I'm certain that the tagmap changes will be made to all drivers as the actual code changes seem to be pretty simple to implement.
In case anyone is curious, the general issue is that the way stuff has been coded in MAME up to this point, people have been doing lookups from a tagmap (a kind of hashmap) on the fly whenever they needed to. The problem is that pulling stuff out of a hashmap is relatively slow, so it's not the kind of thing that you want to be doing in a performance intensive code loop. From what I can see from looking at the SVN commits, the majority of the lookups are now done once up-front when the driver is initialized and stored in member variables. Then when the value is needed in a loop, it can be pulled directly from the member variable, which is far faster. I simplified a little, but that's more or less how it works.
The amount of speed up from these changes depends on how much the driver used to abuse the tagmap lookup method, I assume.