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10.4: A temporary fix for an Exposé slowdown System 10.4
Tiger only hintSeemingly everywhere I turn on Mac forums, users are reporting that Exposé on 10.4 seems unnecessarily choppy with more than three windows (whereas Panther handled this task fine). This problem has been plaguing me for some time now, and it wasn't until yesterday that I began trying to figure out a solution. After an unsuccessful fix of zeroing of my hard disk and doing a full 10.4 system reinstall, I began poking around the graphics tools that come with XCode 2.0 -- since it obviously wasn't related to some third-party program.

I found a property called Beam Sync in a Developter Tools program called Quartz Debug that, when disabled, made Exposé work just as it did on Panther for some reason unknown to me. I'm not exactly sure just what Beam Sync is, which is why I am not entirely sure of the consequences of disabling this -- use it at your own risk! So if you have been having problems with Exposé being choppy on 10.4 even with your Dual G5 and 9800 graphics card, try the following steps:
  1. Install XCode 2.0 from your Tiger install DVD (if it isn't already installed)
  2. Go to /Developer/Applications/Performance Tools
  3. Run Quartz Debug
  4. From the Tools menu, select Show Beam Sync Tools
  5. Click Disable Beam Sync
  6. Force Quit the Quartz Debug application (you need to force quit to make the changes "stick;" regular quitting will re-enable Beam Sync upon quitting)
The catch to this is you will have to do this each time you reboot your computer. But I usually leave my PowerBook on for weeks before I need to reboot, and it's a decent workaround for the time being. Hopefully this will get completely ironed out come 10.4.2.

[robg adds: I haven't noticed any slowdowns in Exposé on either my desktop or PowerBook, but I have seen similar complaints in a few forum threads on various sites.]
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10.4: A temporary fix for an Exposé slowdown | 17 comments | Create New Account
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10.4: A temporary fix for an Exposé slowdown
Authored by: scotty321 on May 31, '05 11:04:23AM

I haven't had any slowdown problems with Expose in 10.4, either on my iBook G3 or my PowerMac G4 Dual 800 MHz. Maybe you should try a clean install of Tiger?



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10.4: A temporary fix for an Exposé slowdown
Authored by: Spartacus on May 31, '05 11:24:05AM

A temporary fix for an Exposé slowdown…

…release the Shift key :-)

Sorry, I couldn't resist.



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10.4: A temporary fix for an Exposé slowdown
Authored by: Wodgy on May 31, '05 11:33:56AM

I'm having the opposite experience. On my Mac Mini (256MB RAM), Expose is much smoother under Tiger than before. With Panther Expose used to be quite jerky.



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10.4: A temporary fix for an Exposé slowdown
Authored by: skia on May 31, '05 12:36:16PM

The "beam sync" you are referring to is the new "Automatic Beam Synchronization" feature of Tiger. This is equivalent to enabling "vertical refresh" on some games if you have a CRT monitor. The idea is your monitor, if it is a CRT, can only display one frame of video per cycle of the electron gun (or "beam") that is blasting the image on to the back of the screen.

The gun starts at the top, moves to the bottom, and then, without "drawing" anything, moves back to the top to start over again. This period where it moves back to the top is called the "vertical refresh". If you can sync all of your drawing routines to that vertical refresh period, then the monitor will display a new frame every cycle of its beam, and your video will be as smooth as is physically possible.

That is what Tiger's "beam sync" aims to do: to take the "vertical refresh" feature of high-performance 3d games and make it an operating-system level feature.

Unfortunately, the implementation seems a little wonky. Depending on how fast your computer is (if it's not fast enough, you may not be able to fit everything into a single retrace and have to wait longer than normal for the next one to come around), and wether you have an LCD or CRT monitor (LCDs don't have a vertical retrace -- there's no "beam" in them), and, apparently, a whole lot of other stuff, auto beam sync may actually slow performance.

There's an interesting thread at the dev list about this:
http://lists.apple.com/archives/quartz-dev/2005/May/msg00170.html

In the mean time, the story is pretty much the same as Q2DX. Test it through trial and error and see which one gives you smoother results. When 10.4.2 comes out, test it again in case Apple has fixed it.

One other note: be sure to test how it LOOKS and not how many FPS you get. Syncing, by it's nature, limits your FPS to the refresh rate of your monitor. An FPS that is greater than your monitors refresh can actually produce choppier results, so limiting FPS is sometimes a good thing ;-)



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10.4: A temporary fix for an Exposé slowdown
Authored by: seb2 on May 31, '05 12:37:33PM

Phew, and I thought I was the only one experiencing an Exposé slowdown.
Not normal on an ATI Mobility Radeon 9700 with 128 MB VRAM.



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10.4: A temporary fix for an Exposé slowdown
Authored by: MoparShaha on May 31, '05 01:34:11PM

Wow, that works really well. The choppy expose action has been one of my biggest complaints with Tiger. Dashboard action also seems a lot smoother.

Thank you.



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10.4: A temporary fix for an Exposé slowdown
Authored by: randalla on May 31, '05 02:41:38PM

This is also affecting both of my machines, which are a 15" 1.5 GHz Powerbook, and a 2x2.0GHz G5. The Powerbook has the 128 VRAM installed, as well as having 1.5 GB of RAM installed. The G5 has an NVIDIA GeForce FX 5200 w/ 64 Megs of RAM, as well as having 1.5 GB of RAM installed. Additionally, the G5 is connected to a ViewSonic VP201b monitor via DVI. Anyway, on the Powerbook, this hint did resolve the issue of smoothness of expose and dashboard significantly. I have not checked the G5 yet, but hope it will. My guess is that only people using flatscreen computers will see this issue. My coworker, with a 2x2.0GHz G5 with less RAM and a 17" DVI CRT (Apple Studio Display w/ ADC connector), does not have this issue at all. He's smooth as silk actually.

I hope this is fixed in a future release of 10.4 :/



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10.4: A temporary fix for an Exposé slowdown
Authored by: cynikal on May 31, '05 05:33:08PM

holy cow!!!!!!

this hint made a world of a difference to my 1.5ghz powerbook w/ 128meg vram. Before i didn't really mind the expose, didn't think it was [i]that[/i] slow like some people i thought were exaggerating.. but wow! panther was not even this smooth! *PHEW*



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10.4: A temporary fix for an Exposé slowdown
Authored by: daulf on May 31, '05 05:47:02PM

I did some research about the effects/reasons for this and came up with the same stuff as skia. I agree that Apple should look into this—but for now, am happy how gloriously smooth this makes Exposé.



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10.4: A temporary fix for an Exposé slowdown
Authored by: drewsaur on May 31, '05 05:50:32PM

Wow, this is exactly what I have been looking for. I was beginning to think that I was the only person who noticed this ugly behavior in Tiger. Made my g5 seem like a step backward!

http://discussions.info.apple.com/webx?13@3.EkoJapaw0hB.1@.68aea1d2/10

Now, can we find a "defaults write" to make this stick?

Drew



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make it stick.
Authored by: skia on Jun 01, '05 03:59:41PM

I haven't tested this, but as I recall, the Q2DX and auto sync preferences are changed back to their defaults when Quartz Debug quits. Thus: if one were to use Quartz debug to set things up the way you want them, and then force quit Quartz Debug, it shouldn't have the chance to turn them back.

Like I said, I haven't tried this. Your milage may vary.



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make it stick.
Authored by: KenaiTheMacFan on Jul 13, '05 08:10:21PM

Force quit Quartz Debug.

---
Ian



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10.4: A temporary fix for an Exposé slowdown
Authored by: unagi on Jul 08, '05 03:50:15AM
found the defaults to change: use this console cmd:

sudo defaults write /Library/Preferences/com.apple.windowserver Compositor -dict deferredUpdates 0 You can verify this by opening /Library/Preferences/com.apple.windowserver in Property List Editor and expand "Compositor"

Open Quartz Debug and reveal the Beamsync tools. change the setting.

Reopen /Library/Preferences/com.apple.windowserver and expand Compositor to see the new setting.

0 = disable beamsync

1 = Auto beamsync

2 = force beamsync

Of course, YMMV.

Enjoy!

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10.4: A temporary fix for an Exposé slowdown
Authored by: jasenko on May 31, '05 08:30:49PM

Great hint, everything seems smoother now.
Great find mate. This hint is one of the reasons why I keep coming here again and again, not just that, it's more valuable to Mac community than any other resource I know of.



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10.4: A temporary fix for an Exposé slowdown
Authored by: FireDancer on Jun 01, '05 03:12:43PM

Expose is smoother but I get horizontal "steps" on the edges of windows and throughout text fields when dragging. For example, when I drag Safari around the screen with this enabled, it causes the left edge of the window to form "steps" as I move it across the screen.

This is on a 20" iMac.... so Bean sync must be doing something for LCDs.



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10.4: A temporary fix for an Exposé slowdown
Authored by: handbiker on Jun 02, '05 08:52:51PM

I also get those "steps" when moving windows around on my PB G4 17" 1,33, but oh boy expose is soooo much smoother!



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10.4: A temporary fix for an Exposé slowdown
Authored by: rlawlor on Aug 11, '06 03:09:39PM

Hey all,

I attempted this fix on my 1 day old MACBOOK intel with 1 GB of RAM. This didn't appear to help. Has anyone else found any other fixes for this ? Any help you could offer would be greatly appreciated.

Thanks



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