Crappy MBP performance when connected to external monitor (!)

[mgpg89]

My MBP (late '08, 4GB RAM, 2.8GHZ) is running noticeably slower when connected to my 20" ACD (in clamshell mode, with the lid closed) then it does on its own (w/out any external display attached).

Anyone know what the reason is? And maybe even how to prevent it?

Thanks in advance!

 

[Darwin]

Any tasks in particular that you notice a decrease in performance?

 

[karohan]

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I have a 2010 MacBook pro and in clamshell mode, I have a very slight, almost negligible choppiness ( probably caused by the gpu having to drove more pixels). How does yours run in extended desktop mode? When I do that I notice a very noticeable slowdown and choppiness in expose and when I am watching numerous flash videos, my other browser tabs would lag win scrolling and such ( this did not happen with just a single monitor).
It's quite annoying and I don't know if our laptops just arent powerful enough to handle 2 monitors seamlessly (or for you, an external) or if it's solely an OS X shortcoming, but it's surely annoying.

 

[c7aea]

My MBP (late '08, 4GB RAM, 2.8GHZ) is running noticeably slower when connected to my 20" ACD (in clamshell mode, with the lid closed) then it does on its own (w/out any external display attached).

Anyone know what the reason is? And maybe even how to prevent it?

Thanks in advance!

Maybe the GPU is working a bit harder. The only difference I noticed is it runs a little warmer. What are you doing when you notice a difference.

 

[mgpg89]

Any tasks in particular that you notice a decrease in performance?

Especially when watching 1080p h264 MP4 videos.
And the whole computer being sluggish in general too.

It does seem to go away for a while when I restart the Mac, so it has got something to do with certain apps running in the background as well.

Any good apps you know of so I can check what's eating up my CPU & GPU? The good old 'system monitor'? And if so, what should I look out for? (don't quite know how to interpret the numbers in the system monitor)

 

[mgpg89]

Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_2_6 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8E200 Safari/6533.18.5)

I have a 2010 MacBook pro and in clamshell mode, I have a very slight, almost negligible choppiness ( probably caused by the gpu having to drove more pixels). How does yours run in extended desktop mode? When I do that I notice a very noticeable slowdown and choppiness in expose and when I am watching numerous flash videos, my other browser tabs would lag win scrolling and such ( this did not happen with just a single monitor).
It's quite annoying and I don't know if our laptops just arent powerful enough to handle 2 monitors seamlessly (or for you, an external) or if it's solely an OS X shortcoming, but it's surely annoying.

When in extended desktop mode, I experience the same issues as I do when in clamshell mode.

Annoying for sure.

 

[BrandoFiasco]

i notice choppiness in graphics and HD Videos when i have my external display connected to my MBP. If i switch from my 9400 to my 9600 it smooths out, so i chalked up my issue to the graphics card being stressed having to drive the laptop screen and another 1080 screen.

 

[karohan]

Is everything equally as smooth with the dual monitors when you are running the 9600m as it is when you are running a single monitor? I've noticed that Expose and other simple things just get a little (yet noticeably) choppier.

 

[borisiii]

I'd say it's probably something besides just the GPU struggling under strain. I have the 2.4GHz 2008 Alu MacBook, and I run it in extended desktop mode (1280x800 native + 1920x1080 external) using a mini displayport to DVI cable. Mine has the 9400m, and there really is no noticeable choppiness/drop in performance. I frequently watch BBC iplayer videos (720p, flash) on the external while browsing (multiple tabs) and editing photos. It runs absolutely fine. Check your activity monitor to make sure there aren't any erroneous processes, as I think you may have some other problem that is affecting performance. Otherwise it may be worth backing up and reinstalling your OS.