For large/complex images it's possible that the image-data arrives in the API *after* the page has been scrolled out-of-view and thus been cleaned-up. In this case we obviously shouldn't cache such page-level data, since it'll first of all be unused and secondly can increase memory usage *a lot*.
Also, ensure that we *immediately* release any `ImageBitmap` data in this case to help reclaim memory faster.
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