Avoid small sampling dots when using PBR

Hello , we had this issue since early version of ue4 . you can see the image below:

there are two simple sphere in the scene, both are assigned same material
with roughness to 0 and matallic to 1.

the problem is when I quickly zoom in/out , or move camera fast , the
reflection between both sphere starts sampling gradually.
and about after 0.5 second, the sampling stopped and leave some tiny dots in reflection area
like this :


The situation gets worse when we use the same setting on water surface , especially when character
stands beside water and look to the water . when we orbit camera really fast , these sampling dots gets
dragged out from character’s edge and become trails. How to avoid this ?

My version is 4.8
Thank you .


You can put r.ssr.quality = 4 in Console Variables.INI and then crank SSR quality up to 100 in the post process. It will affect the performance a little of course.