It is, but the whole experience go together. Just like booting flickers is caused by many problems, but it is about one experience.

I've had the second, and it wasn't related to suspend. For some reason, the GUI decides to do a software bit-blit of the entire screen, which takes tens of seconds, before it lets xscreensaver put up its dialogue box. So don't assume that this is always suspend-related. There are several quite varied possibilities.

Most modern computers can software/CPU blit to a 4K screen at multiple frames per second. So this explanation doesn’t make much sense as is.

Indeed. But since it's so slow that I can see the blit happening, scanline by scanline, it's definitely what is happening, even if it's not apparent why. (I do know that the particular window manager in use decides to move windows back and forth by 2 pixels to work around some sort of bug.)

Not being able to explain why the software does this does not negate the fact that it is doing this, and that it is a quite different possible reason for lengthy pauses in the user interface, one of several, that is nothing to do with suspending the machine; indicating that, as I said, one should not assume that these things are always suspend-related.