I was more after GPU to simply assemble the final video. e.g. my latest project is 1,000 frames, 1920x1080 rendered out as separate .png files. To render to an animation (without any effects initially, though I'll want to add a despeckle, and possibly colour correction filter later) is forecast to take hours.
I could put it together in Blender itself, but Bl lacks a despeckle in the VSE.
Nope, it's the despeckle. Time to find another way.