Bugzilla

Sigh, looks like we won't be getting any help from Apple.

Just to be sure, does changing your Display setting for your external display (from "Scaled" "More Space") on your 2012 iMac make the problems in Safari go away?

As I've said above, I think this bug (the crashes and the glitches) is related to the number of pixels your graphics hardware and software is driving -- the more pixels, the more likely the problem. A 5K iMac has *lots* of pixels, even without an external display. So this bug is much more likely to happen on a 5K iMac.

I don't yet have much information about non-standard Display settings. But I suspect that choosing "more space" increases the number of "virtual" pixels, at least, visible to driver software (in kernel extensions and user-mode libraries), and that "larger text" decreases the number of "virtual" pixels.

Sigh, looks like we won't be getting any help from Apple.

Just to be sure, does changing your Display setting for your external display (from "Scaled" "More Space") on your 2012 iMac make the problems in Safari go away?

As I've said above, I think this bug (the crashes and the glitches) is related to the number of pixels your graphics hardware and software is driving -- the more pixels, the more likely the crashes and glitches. A 5K iMac has *lots* of pixels, even without an external display. So this bug is much more likely to happen on a 5K iMac.

I don't yet have much information about non-standard Display settings. But I suspect that choosing "more space" increases the number of "virtual" pixels, at least, visible to driver software (in kernel extensions and user-mode libraries), and that "larger text" decreases the number of "virtual" pixels.

Sigh, looks like we won't be getting any help from Apple.

Just to be sure, does changing your Display setting for your external display (from "Scaled" "More Space") on your 2012 iMac make the problems in Safari go away?

As I've said above, I think this bug (the crashes and the glitches) is related to the number of pixels your graphics hardware and software is driving -- the more pixels, the more likely the crashes and glitches. A 5K iMac has *lots* of pixels, even without an external display. So this bug is much more likely to happen on a 5K iMac.

I don't yet have much information about non-standard Display settings. But I suspect that choosing "more space" increases the number of "virtual" pixels (at least) visible to driver software (in kernel extensions and user-mode libraries), and that "larger text" decreases the number of "virtual" pixels.