Blackmagic Forum

Hi !

We have not seeing any fusion page performance enhancements for a long time. It is amazing to have fusion tools inside Resolve, but sometimes, even to do some really simple things like using a title preset it get down the fps from 24 to something like 7 or 8 ...

We have a lot of topics reporting performance issues on the fusion page, even with great machine setups.

I personally have in my home an older pc:
windows 10 Pro 64bits / Resolve Studio 17 b6
Intel Core i7 950 24 Gb RAM
GTX 1060 6gb

but at work I have a really better one:
windows 10 Pro 64bits / Resolve Studio 17 b6
Intel Core i9 64 Gb RAM
RTX 2070 super 8Gb

but even in the better PC, the fps stays about 11 max.
we have to wait for the cache is complete, but it is very slow too.
and things at fusion page still really very slow

BUT at Standalone Fusion everything is a looooottttttttt faster!!

I just want to know if can we do any trick to get better performance at Fusion Page (I have anabled cache, and etc, no lucky)

And I want to know from BM if we can expect some enhancements in the future... if it happens DR will be the best software in the world!

Ty

I'm experiencing similar things in performance as you are in the fusion page. One thing I have consistently noticed when performance drops significantly is when the GPU is utilizing anything above 6gigs of RAM on a 8gig card. I'm sure it has some %, but constantly if my GPU goes above 6gigs utilization, fusion is unable to clear the cache to keep delivering frames fast enough. The only way around if for me is to close resolve, wait for the GPU RAM to purge and then restart resolve. I have found disk caching and creating savers and bringing in loaders from those saved frames has helped lessen the RAM usage on the GPU.

From what I'm finding in the fusion page, having more vRAM is the key to a good experience. If anyone with a large vRAM GPU could test this it would help narrow down what causes the slow downs.

Fusion is a generic compositor made for render farms. It's still mostly CPU bound for many of its tools and often single-threaded (the Fusion page in Resolve is missing the Simultaneous Branching option and the ability to render multiple frames at once that is available in Fusion Studio). It's almost the exact opposite of Apple Motion in that regard.

The generic nature of Fusion and the incredible flexibility of being able to build your own tools comes at the cost of performance optimisation for specific tools. It's no suprise that the playback frame rate is low unless you cache to disk.

I've noticed that you have to be very thoughtful in how you construct the nodes. For example, it's much more efficient to generate a single frame of 2D text once and then reuse that frame for any further processing in the rest of the frames. This can be done using the TimeSpeed tool with the speed set to 0 (or maybe the TimeStretcher tool, I usually mix them up). This way I can often go from 2-3fps to easily clearing 25fps. Perform any animation after the TimeSpeed tool.

Caching fusion clips in Resolve is sometimes not working properly, I haven't investigated more though. Even when cached, playback can be slow even if I/O isn't the bottleneck.

I've been playing with converting Fusion comps to Edit Effects, as described in the New Features Guide (basically save a macro in the right place, see Blackmagic Design\DaVinci Resolve\Documents\DaVinci Resolve.pdf > Media and Edit Page Improvements > Timeline Improvements > Convert Fusion Compositions to Edit Effects), and from the little bit of testing I've done so far the performance of the same Fusion comp is far better as an Edit Effect. I may be wrong here as I've barely done any testing, but it blew through the analysis of several Trackers at about 50FPS where they were going about 7FPS as a comp. Take it with a grain of salt though, as this was with different clips, and no visualization as an Edit Effect due to Resolve hanging if you try to enable the Fusion overlays in the viewer - not a 1:1 comparison.

Of course, it's not a replacement for using a Fusion comp, but I'm hoping it'll be useful for common effects that I want to reuse.