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Latest WebKit Builds Address Browser Scrolling Performance on Retina MacBook Pro Models

Soon after the launch of the 15-inch Retina MacBook Pro in June, we pointed to an analysis by AnandTech showing how the need to drive a massive number of pixels taxed the graphics capabilities of the machine to the point where it struggled to hit 20 frames per second while scrolling on resource-intensive web pages such as Facebook news feeds.

AnandTech now follows up with a new report based on a thread in our forums showing that the latest builds of WebKit, the open source browser engine upon which Safari is based, demonstrate dramatically improved frame rates during scrolling.
I grabbed a build (r135516 - it's no longer the latest build but I assume the later builds also contain the fix) and tried it out on the 13-inch rMBP. Scrolling down my Facebook news feed ended up being one of the best showcases for poor scrolling performance on the rMBPs, so that's obviously the first test I ran. As always I used Quartz Debug to measure UI frame rate.
The results show frame rates of around 20 frames per second (fps) under the standard Safari 6.0.2, but jump to nearly 50 fps when using nightly build r135516 of WebKit.


Frame rates approaching 50 fps when scrolling in WebKit nightly build r135515

AnandTech hasn't been able to determine exactly what code changes were made to enable the significant boost to scrolling performance on Retina MacBook Pro models, and it is unclear exactly when those changes will be incorporated into Safari itself, but it certainly seems that a solution is on its way.

Top Rated Comments

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25 months ago
Blur out the names or someone's getting pizzas sent to thier house
Rating: 9 Votes
25 months ago

So why did Apple release a product that clearly wasn't ready yet?


When is anything every ready in this industry?

Everything is in constant motion.
Rating: 7 Votes
25 months ago
Sweet.

It's a shame so many "trusted" review sites (including The Verge) dinged the rMBP and blamed the hardware.... for what is clearly a software problem.
Rating: 4 Votes
25 months ago
Great, that was the major concern I had that was holding me from purchase a new macbook pro: Poor web browsing performance. Kudos to Apple, for working on optimising the code rather than trying to sell another model with faster processor in just a few months. I am so glad they managed to address this as it was rather irritating...
Rating: 4 Votes
25 months ago

Apple didn't do anything, webkit did which is mostly people from KHTML which is what webkit was forked from.


That was ages ago. Today's webkit is a much larger beast than that old KHTML. Go ask Dave Hyatt how much work he's put into Webkit as an Apple employee.

To say Apple hasn't make a significant investment in Webkit is to be either ignorant or foolish or both.
Rating: 4 Votes
25 months ago
Us Chrome users will probably get this waaaay before you Safari guys. ;)

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Very good.

This will be decent band-aid till rMBPs with excellent performance are released with Haswell.


This isn't a band-aid. The issue has never been lack of GPU/CPU power. You can scroll smoothly on much older hardware running the 30" ACD, which is the same resolution as the 13" MBP Retina. It has nothing to do with pixel pushing power.

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This isn't the only area where lag is found. There is general UI lag in the OS as well. Not to say that there isn't some software issues there as well, but they have a lot of evidence that GPUs just aren't up to snuff yet.


The GPUs are fine, stop repeating this non-sense. My nVidia 9400m equipped unibody MacBook could run a 30" ACD with dual-link DVI without issue, at 2560x1600. Why do you think an Intel GPU 3 generations newer couldn't do the same ?

It's obviously a bug in the software stack that has to do with the way Retina scaling (HiDPI) occurs.
Rating: 3 Votes
25 months ago

.

Very good.

This will be decent band-aid till rMBPs with excellent performance are released with Haswell.


Err.. or it's a software optimisation issue, as this clearly points out.

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it's the hardware. rMBP switches over to intel graphics 4000 which can't handle the amount of work needed for smooth UI


Bullcrap.
Rating: 3 Votes
25 months ago

That's incorrect and has been pointed out a gazilionth times here. It has everything to do with pixel pushing power, the ACD might have the same resolution with the 13" mbp, in the later the resolution is doubled and then halved (or adjusted to some %) to fit the screen. Thus it's the overhead to run 4 ACDs (no of pixel quadrupled) not one, plus the processing cost of then adjusting it to the actual screen size. When the no of pixels you render are QUADRUPLED you bet it has everything to do with pixel pushing power.


You're saying the same thing I am except making a few wrong assumptions. The resolution isn't doubled then halved at all in HiDPI mode, it's only downscaled after upscaling if you use the scaled modes (1680x1050 or 1920x1200). Running at 1440x900 (2880x1800) only upscales non-Retina graphics to 2880x1800 and leaves it at that. Running 1920x1200 (which I run permenantly) runs a 3840x2400 framebuffer which it then downscales to 2880x1800 for displaying on the display.

And what I've been saying all along is quite correct, the problem is not the pixel pushing ability of the GPU. Pixel fill rates, look them up. Again, if you can't understand that a 4 year old GPU, the 9400m, could power a 30" ACD and that we're now in 2012, 4 years later, with GPUs 3 generations newer, I don't know how to explain it to you.

The 9400m could push 2.32 GP/s. Again, 4 years ago. 2880x1800 at 60 fps is roughly 311 MP/s. Are you getting this ? Even if what you say is true and HiDPI was so horridly optimized as you claim (which it isn't), that's still only half of the pixel fill rate of a now 4 year old Integrated GPU.

Anyway, I own a rMBP 15" and I've hardly met any "lag" whatsoever. I guess some people are just too sensitive. Thank god Apple knows it's a software issue and is fixing it for those people.

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It's not a bs argument, it's not powerful enough indeed. The ui still lags and stutters. The current hardware is just not capable enough. It's an air cpu circa rev. 1. Apple have hacked their way to resolution independence with rendering twice the resolution canvas so as to avoid what win 8 did and go into detail about interface elements. They thus offloaded all the complexity on the hardware, and the hardware isn't there yet. Simple as that. Rev. 1 retina macbook pros are a major compromise. I am still planning to go ahead and buy one, fyi, but If I do I ll be do it in fully aware that I am buying a problematic rev. 1 product, not only for the image retention issue with the lg screen, but also for the gfx barely making it there.


The hardware is capable. You just don't understand GPU hardware or HiDPI to make such claims. Anand has always been full of it.
Rating: 3 Votes
25 months ago
Damn the difference is incredible on my 2011 Air! In fact everything in the browser seems so much faster.
Rating: 2 Votes
25 months ago
This is great not only for the Retina line!

My 15" rMBP is flying now :D And my 2009 iMac too :D
Rating: 2 Votes

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