Very good news @agriggio !!!
I have now prepared a new AppImage based on my Ubuntu 14.04 docker container, using a cleaned procedure to assemble the application bundle.
I tested it on an Ubuntu 17.04 system and, as far as I can tell, the UI is as responsive as a native build. Could you give it a try as well? The package can be found here.
If this package works correctly, I would then dare to say that I have a solution to propose for the automated creation of an RT AppImage via Travis CI… The only thing I still need to check is wether
-O3 is being used in the build process, and wether the LensFun database is correctly updated before copying it into the bundle.