I've been doing some work which needs field rendering. And for reasons I won't go into I don't want a time difference between fields . . .
the problem is I also have an envmap, and Blender insists on recalculating it for both fields, even though it will be the same, so if someone could implement a simple check I'd be grateful. It would cut my render time in half.
Secondly, field rendering appears to produce some really nasty shadow artefacts (on static scenes). I'll try posting one soon.
(apologies if the wrong forum, I'm still not sure about round here!)
I have had the 'X' pressed, since I need to have no time difference for my use for it, but it then renders the (same) envmap twice for each frame.
EDIT: as regards the 'static scene' just to say that I encountered the artefacts without movement, whereas had not 'X' been pressed I'd know you'd get the breakup lines from fields etc. I'll try your ideas out for that, although I must confess I've never worked out what the 'bias' control actually does.