13 Replies Latest reply on Jul 2, 2009 2:26 PM by Adolfo Rozenfeld

    Render is slow with Multi-Processor

    Stacy Rothwell

      I have a Mac Pro with 8-core and 8GB RAM.

      When in AE 8.0.2 I have Multi-Processor turned on and when doing 100% Full Previews, it renders as fast as you'd expect a machine like this to render.... fast.

      But when I go to render out, it is a lot slower than the preview. The only thing I'm turning on in rendering out that's not in the preview is field rendering. So, in theory, I would maybe expect it to be twice as slow. But it's like 10x slower.

      I have seen other posts where it says to go into AE preferences file and set MaxProcessors to 4 so that each eligible core gets 2GB of RAM. That did not help.

      In fact, I use MenuMeters and I still see all 8 cores being used in the render.

      Other than turning on Multi-Processor support in Preferences, I haven't changed any of the other settings (RAM cache, percentages, etc) from default.

      Anyone have any idea of what might be going on here? It would be most appreciated.

      Best regards,

        • 1. Re: Render is slow with Multi-Processor
          Mylenium Most Valuable Participant
          The render performance is also dependent on your disk performance as well as the target formats. Certain Quicktime formats don't work particularly well with MP enabled. On the other hand your renders might go quicker than AE can append the files or write them to disk. Both conditions do not apply when creating RAM previews. You should try a test with an image sequence and see if it goes any better. The RAM allocation as such schould not be the problem. Even with 8GB there is usually enough headroom left if you are working at SD resolutions and are not throwing around too many effects.

          • 2. Re: Render is slow with Multi-Processor
            Jonas Hummelstrand Level 2
            Enable "Show Rendering in Info panel" in the preferences and make sure your Info panel is visible while previewing.

            Then twirl open the "Rendering Detail" in the Render Queue to see what is taking so long. I recently had really slow renders when my disk was almost full, it took 10 seconds for every frame to do "Compressing & Writing."

            - Jonas Hummelstrand
            • 3. Re: Render is slow with Multi-Processor
              In my experience, AE multiprocessing w/ 8GB RAM is the slowest option. A lot slower than regular AE render. Perhaps Nucleo Pro will do what you want. It really does do what it is built to do.

              I'm curious, do you get 29.97fps RAM preview realtime? (I'm having issues with that on my 8-core MP...)
              • 4. Re: Render is slow with Multi-Processor
                Stacy Rothwell Level 1
                I do get great RAM previews.... too me a while to be sure to turn off the Blackmagic output.... that will make your RAM preview on your computer's display suck.
                • 5. Re: Render is slow with Multi-Processor
                  Jonus..thanks! I just wanted to say that you have really saved my day, today. The reason being is that I finally figured out where the render detail is displayed. I hadn't noticed that twirly down below.

                  Today...i was able to see why my renders were going horribly long! Like I mean 30 hours and 40 hours. I opened up that info panel and I realized that AFX was rendering unecessary compositions which I turned in invisible with the opacity settings (believing that AFX wouldn't render invisible things).

                  Well I was wrong! The several hour section has just turned into a few hours!

                  Thanks man!!

                  • 6. Re: Render is slow with Multi-Processor
                    Mylenium Most Valuable Participant
                    *ouch* Yes, just twirling down opacity would still render the comps as it makes AE think it needs to evaluate the Alpha channel information. You should instead turn off the layers completely, or as an alternative, at least turn them into guide layers (which by default will be ignored for final rendering).

                    • 7. Re: Render is slow with Multi-Processor
                      Jonas Hummelstrand Level 2
                      Mylenium, are you sure about that? Something with Opacity set to 0% shouldn't influence anything that I can think of. I would consider that a bug.

                      I just did a test and setting a bunch of animated layers to 0% opacity made AE render 500 frames of animation in 0.5 seconds, so AE is still looking at the layers but it seems pretty quick to determine that the layer doesn't need to be rendered.

                      - Jonas Hummelstrand
                      • 8. Re: Render is slow with Multi-Processor
                        Mylenium Most Valuable Participant
                        The question is, whether they are really properly set to zero. They may be just at 0.0001. it may just not be visible on the interface because the value gets clipped. Therefore turning off the layer entirely would be the safer route. Of course properly zeroed out values should not be evaluated whatsoever and thus not have any influence. Sorry for the confusion.

                        • 9. Re: Render is slow with Multi-Processor
                          Andrew Yoole MVP & Adobe Community Professional
                          My understanding is that AE checks for a 0 opacity level before all other calculations, and if it IS 0, won't bother with any calculation. I imagine that Mylenium is correct, any value other than true 0 will require processing of the layer.
                          • 10. Re: Render is slow with Multi-Processor
                            Rueberm Level 1

                            I know this is an older post... but I find that AE usually renders faster when mulitple freames is not enabled... I would love to see this speed up the process but it will turn my 10min render into a 2hr render.

                            • 11. Re: Render is slow with Multi-Processor
                              Adolfo Rozenfeld Adobe Employee


                              It depends on many things.

                              If you don't hae enough RAM (2 GB per core), MP may slow down things.

                              It also depends on the nature of your project. If your project is more hard disk intensive than CPU intensive, multiprocessing can slow things down ratehr than speed them up.

                              • 12. Re: Render is slow with Multi-Processor
                                Rueberm Level 1

                                8 core system 2.66

                                8 Gig of ram

                                raid 10 and raid 0 hard drives


                                Right now I am animating a story book from psd files... they are large files that I have scaled down to 720p

                                I set up the multi frame settig up to use 2 processors and 2 (then 2.8) gig of ram.(I tried several settings and this was faster by an hour... of course it only took 10min when I did it without multi frame enabled) Nothing else was running.


                                Some times using the multi frame setting is faster but usually not.

                                • 13. Re: Render is slow with Multi-Processor
                                  Adolfo Rozenfeld Adobe Employee


                                  Most, but not all, projects show significant speed-up factor when using the Render Multiple Frames Simultaneously.

                                  So, if your project is memory intensive rather than CPU intensive, that can be the case. There are also a couple of video codecs (for example, Sorenson video) which can slow things drastically when used as source or target files with MP on.


                                  Also, I notice that many users expect to find a magical MP settng in Memory and Multirprocessing preferences that will make things render faster.

                                  There's no magic setting. If you have adequate RAM and the nature of the project benefits from multiprocessing, the default settings will work perfectly.


                                  You want to depart from the default in two typical cases I can think of now:

                                  • You don't have enough RAM to feel all cores in your computer ("Leave X CPUs free", as is your case).
                                  • Instead of maximizinng rendering performance, you want to keep some resources to keep working in other applications ("Leave x CPUs free", "RAM to leave for other applications").