Jittery parts in assembly

We have an assembly that contains 250 parts, however when fasteners are added (either via toolbox or vendor supplied (native SW)), and the assembly is rotated, all parts seem to jump around as if unmated (reciprocates). We have adjusted level of detail on Performance settings (both high and low) with no changes.  Has anyone encountered this type of issue(s).

Thank you

SolidworksAssemblies