Redraw Viewport CPU Profiling (Rendering)

Hi, Working on a VR project, struggling with optimization of the project. i fixed so many of bottlenecks but still each 2 seconds i have frame drops, according to the profiler RedrawViewport is the cause of it.

Tried to disable all HUD, UI, TextDraws and …

Reduced the draw calls almost to zero (used console commands)

none of them worked! what is the definition or the duty of this event “RedrawViewport” ? so i know where should i work on to reduce the processing time on this task.

Thank you very much for the time you guys spending to read and answer each question.

I am having this exact same issue in UE 4.20. RedrawViewports is destroying my performance. Can anyone shed light on this? Does a glossary of profiling terms for UE4 exist?

Actually , i found out my self what was the problem.
some times for HUDs or Text renders controlled by code or blueprint .
there was too much refresh rate (updating the variables related to the HUD or texts at every frame)
one of the juniors designed the bad logic for updating one element of our HUD and funny enough no one reviewed his code at the office before he push it to the server.

there is no way to find out what object exactly causing the redraw process except review every class related to text renders and HUDs . FYI. scene capture components show them self as redraw too!