Render speed 700% slower because of expressions?
I've created a very simple, JSON driven lower-third in AE, whose layers are automatically sized, positioned, formatted and animated. It consists of 2x text, 2x shape layers, 0 effects–apart of sliders–and 11 expressions.
Render time, w/ expressions in AE: 42s
Render time, w/ expressions in aerender: 42s
Render time, w/ expressions in AME: 14s
RAM preview at full resolution, w/ expressions in AE: 5s
Render time, w/o expressions in AE: 6s
Render time, w/o JSON, but w/ expressions in AE: 14s
This happens under Windows 10 and OSX 10.12 on two separate machines; I've taken care of purging the disk cache in between each render, and been rendering to lossless as a test.
Also worth a mention: If you have access to an Apple Silicon Mac, try using AME Beta 22.1.1 - this problem doesn't seem to exist there. It still does exist on an Intel Mac using AME Beta 22.1.1 though. So probably not hugely relevant.
@Rashid Thanks for the thought. I do feel it is memory related, as if you increase the allocated memory to Adobe apps whilst AME is in the middle of a tortuous 8-hour render (the same one as I mentioned in my first comment) then the remaining frames briefly speed up again, the remaining estimation goes down whilst it uses up the memory boost, but this soon levels out again, so it's a brief reward.
It would also explain why the first portion of the render goes quickly: this is using all the available RAM, and then it starts going slow when virtual memory use kicks in because too much memory is being used.
Just guesswork, though.
Rashid Ghassempouri commented
We had performance issues with expression rendering :
Maybe it can temporary help you until a real fix happen.
Bumping this, as it's now 2021, After Effects 22.0.1 is out, and the same problem is happening all over again. If I strip all expressions/behaviours from a comp and render it, it's nice and quick... I mean a 6 minute sequence renders in about 10 minutes, which is about right. If I keep some basic expressions in place (okay, I'll be specific: Face In+Out - msec, and Wiggle - position, neither of which should be particularly taxing) my renders drop to hours (estimated around 7-8 hours).
This is also happening on both Mac and PC.