[dubir]

Please advise how to avoid long time render when rendering close room with ceiling and no windows .
Thanks

[Bubbaloo]

In addition to your interior scene lights, you can put in some hidden emitters to add some noise-clearing fill lights. More light = faster clearing.

Also what I like to do to get nice lighting and reflections in interiors is to delete the wall behind the camera and use a nice interior HDR environment.