It matters to me because when I'm "in the zone", every second spent waiting for a compiler to do its thing is a small loss of focus; ideally I'd like incrementa

It matters to me because when I'm "in the zone", every second spent waiting for a compiler to do its thing is a small loss of focus; ideally I'd like incremental compilation time to be below a second. Your brain may be less sensitive to this latency, but I think loss of focus happens to everyone to some extent. The cost of template instantiations by itself is not too significant, and they ought to be cacheable in the future C++ module system, along with the header file parsing that's the biggest factor making C++ take longer to compile than, say, C. But with today's compilers, it all adds up.