This app?
https://github.com/RoundedTB/RoundedTB/releases
From the link:
"Seriously, RoundedTB started off as a tiny proof-of-concept months ago and I just sorta piled a load of code on top of it, so it certainly needed a tidy up."
Seems more like a Beta version versus being a final release that would hopefully load and configure faster.
My suggestion is to address the problem to the developer.
Also, what other things do you have automatically starting up?
Those sort of things take a lot of time and resources.I have Lively wallpaper and it too takes time like RoundedTB. They both come into action at the same time after boot-up.