Vsync on = block placing lag

I had forgot to turn on Vsync (as usual) so I did and when I place my grass block in front of my it became see-trough (like x-ray) for about a second.
Block update instantly fixed it.

But it all looks like while in Vsync mode it can take longer for a block to load when placed as of this not happening while Vsync is turned off.

I'm not 100% sure, but I think it's only under a period after you change the Vsync to on.

I would give you a picture if it wasn't so hard to catch it.