Faster way to show layer mode changes

When working with raw images they are large and thats why it takes time render hole image when check different layer modes effect…
Suggestion is there way to use small preview window like this navigator on 2.08 to show what ex layer mode change could look like – perhaps “Apply button to that” like in effect and Looks.
When working with small images this not so bad must there plenty of users which work larger originals