In framework 2.9.9 release, we’ve implemented lazyload method to load all Builder assets (ie. it won’t load any Builder related css/js file unless the page has Builder content). During the rendering time, there is a little delay in loading the scripts and css which is causing that rendering issue before the page is completely loaded. We are aware of this matter and will be implementing enhancement soon.
UPDATE: This issue is fixed in Themify framework 3.0.3 release.