This can be considered normal behavior, actually. I have a site with a slider and a widget area with custom widths per widget. This site, too, loads with very similar artifacts that you describe. I have not been able to find anyway to prevent this behavior.
The final release of Weaver Xtreme V3 will have new code that dramatically improves the speed of full width areas in the header, content, and footer. I have yet to test if this new code improves my site with the loading behavior.
The solution I’ve adopted, and which will be included in the final Weaver Xtreme Plus plugin Version 3 in the near future, is to use a loading screen plugin. I’m currently using LoftLoader plugin with a custom logo, and it really works quite well on the page with the slider and custom width widget area. Weaver Xtreme Plus will have a more integrated version.