Embedded view vs component loading performance

I wonder why a simple embedded view has very slow loading startup vs perspective component.
For example is following example I try to load several custom button that only include a Label and two icon as embedded view. As it shows they loaded very slow but if I create this page with native perspective button they load instantly.

I didn’t see this problem for template in Vision.

Not that the performance doesn’t suck in this case, but comparing to Vision is utterly meaningless. The architectures are so different that techniques and layouts that are fine in one can be horrible in the other.