When a vertical menu is rendered, the arrow denoting a sub-menu starts out in the wrong position, left aligned against the menu item text, and then moves to its correct right aligned position.
Sometimes this is barely perceivable, but other times is very noticeable, mostly during navigation. See the attached GIF for an example of the issue.
I suspect it has something to do with page resources loading (e.g. CSS).
I am unable to reproduce this with Kendo UI in the Dojo, but this is probably because the menu is not rendered on page load.
It is mostly noticeable in Chrome, but can be seen in Edge and IE (it's difficult to tell with Edge/IE because their rendering in general is terrible).
Code used for the menu:-