A NULL build takes ~4 secs for AOSP and ~8 secs for real Android targets (with hot disk cache). Better than 1 or 2 minutes, but still slower than we want it to be.
I'd like to optimize ninja and kati. The goal would be... ~3 secs for real Android targets??
Introducing binary build.ninja (similar to .pyc for .py) seemed to be an idea. I've sent a proposal to ninja-build@. We'll see.