Extreme slow rendering of the ofx plugin

Hi, i did some roto work in Fusion 9 with the OFX version of mocha VR. (the latest release) It was a sequence in HD 1080 p with about 180 frames.
Tracking an the Roto work did work well, but using the result i almoast imossible. when i activate the rendering of the matte it becomes insanely slow… i decided to export the matte as imagesequence which took about 2,5h …

i can not really understand why mocha i that slow since the scene contains only rotosplines and some tracking - nothing else.

i have a dual xeon System with 32 GB Ram and an Gtx 980ti… WIN 10

i tried hte project in DaVinci too, with no success - mocha i extremely slow…

any ideas what is happening ??

Hi there,

That’s very odd and sounds frustrating, I am passing this to the dev team to see if we can do some tests.


That does seem abnormally slow.

Can you check your GPU preferences and make sure the Amount of Texture RAM to Reserve is 50-75% of your GPU memory? That may help alleviate some of the issue.

How many layers of roto are you using?

Hi Martin,

I increased the memory slider to 75 % - the strange thing is that it shows about 10.000 Mb in this position although the GTX 960TI only has 6 GB of RAM… so I#m not sure if Mocha reads out a wrong number or possibly tries to use the system memory in addition ???

Im using about 30-40 Layers of roto… some layers are tracked some attached to a tracking layer - Some are additive and some subtractive … no motionblur

In my understanding a quite simple roto session…


There are two memory sections:

  • “Max amount of memory to use” which can stay at 80%. This is your RAM
  • “Amount of Texture RAM to Reserve” in the GPU tab of preferences: This is your VRAM. Dial it up to about 1024. (You don’t need as much as I thought!)

Having said that, it does appear as though Fusion renders our shapes abnormally slow.

The workaround is to export the comp shapes from Export Shape Data, which is more tedious, but at least you’ll get the performance.

We are going to profile Fusion to see if we can work out where the render bottleneck is. I will file a bug.

HI Martin,

thanks for your reply – I’ll try this approach…

Please profile DaVinci too, because the problem is there the same in Mocha VR and Mocha Pro.


We don’t currently support Resolve in a number of areas as there is some work on Blackmagic’s end that needs to happen to make Mocha Pro a fully functional OFX plugin.

Hopefully we can work something out with their team.

Hi Martin,

are the problems in the Plugin version of Mocha solved in the new version? (2019)

Or is it still running slow in fusion?