Performance a bit slow on my iMac (5K, Late 2015)

[MacInWin]

Harry, a small prediction on my part (not a true prophesy, as we are supposed to stone prophets who get it wrong): Sometime soon, I think, the hardware makers will volunteer to "help" get high speed access out to the remoter areas. Here in the US, Google is already installing fiber backbone to the home in some locations, others will probably follow. That largesse will be, at least in part, motivated by the thought of selling "smart terminals" to the masses and then charging for cloud storage. But to make that scheme work, the high speed network has to be in place. Personally, I think Google just wants to see where everybody is going in the Internet to sell that to their customers, so having control of the internet access will give them the perfect place to filter the packets for that information. Chrome already passes that information to the mothership, as do all Alphabet products, but with the backbone under Google's control, all that data they cannot currently get to will be theirs.

 

[bbnck]

Hello,

Just a quick update: given it was close to Christmas the last time I e-mailed Craig, I haven't heard back from him yet. I reached out to him yesterday to see if they have found anything from the logs I sent in November, so I am hoping he will get back to me soon. It has been quite a long couple of months, so I am hoping being patient has paid off if the time it has taken is because they are wrapping up a software update to address the problem. Bluntly speaking I just want to know if it is a possible hardware issue that requires me to go to an Apple Authorised Service Provider or is just a limitation of the hardware, or a software problem which they can fix. I am hoping it is a purely software issue, but I have my doubts.

I really hope I have an answer soon.

 

[bbnck]

OK, final update.

After much investigation, it turns out the GPU is running out of vRAM when the animation stalls occur. Quite literally it is being caused by the amount of pixels the GPU needs to animate. With the Retina display, a full screen window is 14 million pixels alone - combine this with lots of other large windows and it can overwhelm the capacity of the GPU. I have found maximising windows has a significant effect on how frequently animation stalls occur - if I have lots of applications open but keep their windows unmaximised, animation stalls may not occur at all.

As I previously mentioned, I had submitted a complaint about this to Craig, and he had responded shortly afterwards asking me to forward over some sysdiagnose logs and a video recording of the problem so that they could investigate. After waiting several months, he told me they see some use cases that can benefit from further optimisation, but confirmed the problem is ultimately caused by the system running out of vRAM.

I don't know about you but I am certainly wondering why Apple decided to use a GPU that could easily be overwhelmed by the Retina display, but at least this issue comes to some kind of close and I am reassured knowing it is not an underlying hardware problem.

I should also mention I recently went to my local Apple Authorised Service Provider as the display was suffering from significant image retention, especially at high brightness levels. When I went to collect my machine, I tested an iMac they had on display as they also happen to be an Apple Authorised Reseller and I noticed the same animation stalls under the same conditions on the machine I tested.

 

[ferrarr]

Everything has limitations. Just because you want to exceed the vram for your machine, millions of other users are completely satisfied with their Macs performance.

 

[bbnck]

Everything has limitations. Just because you want to exceed the vram for your machine, millions of other users are completely satisfied with their Macs performance.

As you do not have a Retina iMac and have first-hand experience, you cannot realistically be objective about this issue.

It runs out of vRAM in usage scenarios which are entirely reasonable for a machine with this kind of processing power, but Apple has elected to use a GPU which struggles to keep up with the Retina display. It results in a poor user experience.

 

[chscag]

It runs out of vRAM in usage scenarios which are entirely reasonable for a machine with this kind of processing power, but Apple has elected to use a GPU which struggles to keep up with the Retina display. It results in a poor user experience.

Not that this will help you (too late for that); but Apple will be using a more robust set of GPUs with additional vRAM in the new iMac models which will be released later on this year. We will have to wait and see exactly what they look like but it seems that they at least realize that improvements were needed.

 

[bbnck]

Not that this will help you (too late for that); but Apple will be using a more robust set of GPUs with additional vRAM in the new iMac models which will be released later on this year. We will have to wait and see exactly what they look like but it seems that they at least realize that improvements were needed.

How do you happen to know this for certain?

 

[pm-r]

How do you happen to know this for certain?

Sorry for butting in here, but a quick google search seems to confirm such rumors:
https://www.google.ca/search?client...-8&oe=UTF-8&gfe_rd=cr&ei=lOegWMCZNIHt8wfdkoM4

and this is typical:

The iMac 2017 is also rumored to pack in support for VR or virtual reality and a powerful GPU to offer an enhanced user experience. The device will reportedly house either a Polaris 11 or Polaris 10 GPU from AMD.

- See more at: http://www.techtimes.com/articles/1...pple-fans-be-excited.htm#sthash.w0qCsMGS.dpuf

 

[bbnck]

Sorry for butting in here, but a quick google search seems to confirm such rumors:
https://www.google.ca/search?client...-8&oe=UTF-8&gfe_rd=cr&ei=lOegWMCZNIHt8wfdkoM4

and this is typical:
- See more at: http://www.techtimes.com/articles/1...pple-fans-be-excited.htm#sthash.w0qCsMGS.dpuf

Interesting, thanks.