I was not able to reproduce this with Gnome. And it looks like bug 1502516 further regressed and is now present even without GPU process... :/ So this picture caching bug might be a consequence from that.
Bug 1518796 Comment 2 Edit History
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I was not able to reproduce this with Gnome. And it looks like bug 1502516 regressed further and is now present even without GPU process... :/ So this picture caching bug might be a consequence from that.