efficiency of object sources and collisions?

[Rif]

"does the level of poly detail of the collision objects or object based emitters make a huge difference to a fume sim?" "Would I be better off with really simple poly layouts for my objects or will fume do its own voxel subdivision around the object relative to the size of the ffx grid? "

Nop objects get Voxelized in the grid based on the Spacing amount and isnnt related to topologie as far as i knowand iv seen..

"more to do with the particles radius controls being like the volume of the simple source? "

Yes for the radius at first .. When doing an FFx Sim with Particle Base , this is the Parameter that you want to tweek at the first .. U dont want to have a Radius bigger than a Cube of the grid basicly ..Your goal is to avoid that.. And i know its hard cause of no Viewport ( "AB Stile" ) Particle Radius Visualisation but its still manageable ..

and Then , Blur Source Object checkbox in the OBj\Src Tab is also helping his part ..

Also use Subsamples if needed based on the speed of what u got moving per particles and how much velocity your pushing from them !

Again , i suggest building u r volume with lots of small particles disturbing and pushing ..

Also , you can use the AFC Curve in the Rendering Tab for Controling Opacity of the Smoke ( but so that the life of the smoke dies smoothly and no poping ) .. u can even create crazier effects playing with that shading afc..

hope that help ..