After struggling with the starting delays of RT 5.3 and finally got a developers version that is starting up fast:
I continued exploring this intriguing and surprisingly good piece of RAW conversion software! 
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Then I was wondering if things like the U-point technology I was used to work with in Nikon’s CaptureNX2 and the Google NIK plugins for Photoshop, are also possible in RawTherapee.
To my big surprise, there was indeed a (special?) version of RT, called the LocalLab Build which implements U-point like technology. Bravo for that!
But, what I don’t understand, why is that a separate version? I tested the:
Version: 5.3-473-gcaafa472
Branch: newlocallab
version and it works surprisingly fine using local control points for adjustments.
Even the start times on my Windows 10 system is only about 3-4 seconds! And ‘Preferences’ window opens almost instantly. So it seems the other performance enhancements are also implemented in this ‘newlocallab’ version. But why is this not the standard version of RT?
Why can’t there be one version of this great RAW converter with these features included?
Is there a specific and/or special reason for that? Because to me, the user, I only see an extra icon, the ‘Local’ cross-type symbol in the edit window, I can use. So why not integrate it in the ‘normal’ version of RT?