HDR dome light vs vray skylight speed

[tricky]

I'm doing an interior animation of an apartment. I'd like to use a HDR in a dome light for the lighting to add the HDR-subtleties. Am I right in thinking that using a HDR for lighting will be a shed-load slower than using a vrayskylight system, or should I be able to get similar rendertime results?

[Morne]

In my experience its way slower. Unless maybe its a blurred lowres HDRI?

[tricky]

I've done a few tests using a HDR and am trying to improve render speed. At the moment, I am using the vraysky and vraysun for GI but I have a Peter Guthrie sunny HDR in my reflection overide. It looks OK, but I cannot clean up sparkly pixels in my reflection element. You can see these bright speckles in the beauty pass too which will dance with an animated camera.

Can somebody give me a solution to this, if there is one?

[Morne]

What if you change the HDRI into a LDRI (an 8 bit image) If its just for reflection, maybe this could work?

alternatively stick the HDR in a dome light and set it to only affect reflections, then up the samples for this light to something between 128 and 256 or higher (depending on your dmc and aa settings)