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Amazingly slow renders with CS5 on I7 8 core

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Jean Piche
Amazingly slow renders with CS5 on I7 8 core
on May 15, 2010 at 9:58:16 pm

Hi folks,

I am picking up a post about rendering on new Apple machines with CS5. I obtained gracious and helpful responses from this board a couple of weeks ago about the same problem. However, after trying all sorts of things, rendering speeds are now even worse. So i am starting to wonder what is going on.

I am a ten year AFX veteran, by no means the most advanced but competent enough to know if I do something stupid.

My hardware:

Month old machine, MacPro I7 2.93GHz 8/16 cores, 32Gb of RAM, 8Tb of Disk space (new drives)

I have tried just about all possible settings. The fastest I can tell is this:

Render multiple frames is on.
Dedicated CPUs: 10 (out of 16 virtual).
Dedicated RAM per core: 2 Gb
Cache on or off makes no differene


The single source file is a 10 minute animation video @ 5760x1080p out of which the central 1920x1080 is rendered to a new file. The source file is sitting on one of the 7200rpm drive. AFX is rendering on the same drive. No layer overlaps,no effects, no lights, no 3D, no masks, no featherings of any kind, no speed manipulations.

Time required for render: 3.5 HOURS.

Admittedly this is a large source file but the disk activity monitor shows disk read/write cycles on the order of 12/15 MB per sec. which is about one fifth the capacity of the drive and using a different source file of 1920x1080 comes out the same way.

Of course I can do the same project in FCP or even in Quicktime7 edit in less than 5 minutes but something is badly amiss somewhere in my setup and I cannot find out what it is. Is it actually possible that the machine/CS5 woudl be so slow?

While rendering, AFX seems to startoff like a bomb (as it shoud) and gives me an estimated 20 minute render time for the project. That is for the first 500 frames. As it gets further, it slows down dramatically and eventually settles to a pace that involves running around in circles doing humongous page swaps and staying on the same frame for close to a minute and then burst writing 10 or 15 frames and then jamming up in swap again.

My activity monitor shows all 10 requested CPUs with their 2 Gb fully loaded and AFX itself running about 3.5Gb. When swapping, all cpus sit back at close to 0% workload while the system does god knows what. I am showing close to 60 Gb in page ins and page outs...

My question thus would be: what am I doing that is so completely killing the machine. I would believe teh size of the source file as a culprit, but the thing does exactly the same thing when the source file is 1920x1080.

Anyone from Adobe or Apple around who can comment?

Thanks ever so much....


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Todd Kopriva
Re: Amazingly slow renders with CS5 on I7 8 core
on May 15, 2010 at 10:55:40 pm

How much RAM do you have reserved for other applications?

What other software are you running at the same time?

You say that you have 2GB allocated per background process. I'd recommend more like 4GB per background process, because your sources are around digital cinema size. (The preset values for RAM allocation only go to 3GB, but there's a comment on the bottom of this page that shows how to use other values.)

I wrote these two blog posts for the exact purpose of telling people how to optimize performance:

Todd Kopriva, Adobe Systems Incorporated
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