Suggestions for quick to render blurry refractions

[tricky]

I have lots of little LED lights (vray sphere lights) behind a thin (2mm) piece of coloured plastic. I need the plastic to blur the lights, and the only method I can think of is to use blurry refractions. This takes ages to render though. Any suggestions?

[tricky]

Ignore. We had broken lights. replaced and it worked out better!

[kosso_olli]

Vlado said somewhere that some major speed gain is to be expected in V-Ray 4.0 when rendering blurry refractions.