Ingo is away on holiday for a few weeks.
Yes. From the release notes,
Both the speed and stability of various tools and of RawTherapee in general were significantly improved
To get an honest comparison you should checkout the same commit, compile once using
Copy the build somewhere, and compile once again using
-DPROC_TARGET_NUMBER="2" (optimized for your CPU)
Then compare the builds.
Also note that processing a file just once is not reliable. Run a command several times and take the average. There is a script in the repo which does that:
Please contact the repo maintainer about that.