Most efficient method to map HDRI onto geo - in terms of sampling

[DPS]

I've mapped a dusk hdri pano (on a street with skyscrapers) to geometry of the buildings to use for GI and reflections. Wondering what the most efficient way is to do this so as to avoid speckles from the bright areas and be as efficient as possible?

I currently have the vray HDRI in the self illumination slot within a vray material.

Also is there a way to clamp the HDRI to a specific value anywhere? Clamping eliminates the problem but I obviously then loose my dynamic range

[svetlozar.draganov]

The best way to avoid speckles and still preserve the high dynamic range of the HDRI is to use the new Max Ray Intensity parameter in V-Ray 3.x which will only clamp the value for the secondary rays.
A quick tutorial of that parameter could be seen here: