Its not just annoying, its a sign that memory management (browser engine) is failing somewhere. When devices started having that problem (my 1st gen iPad for example), that was in part because the pages were to heavy, but also because of the way pages were cached into memory (not compressed) and the expectation of the UX that you'd only want to view one tab at a time (testing/QA and preference thingy).

Little details like that tend to reveal a lot about the goal-setting aspects of the development processes. Not a knock, just a revelation.