There was a comparison in Call of Duty WW2 beta which showed even the 7400 struggling to maintain 60 fps, where the 7700k and 8400 had 95 fps. However, if on a gtx1050 or so, you'll be capped around 60 fps anyway in newer games.
The 8400 had VERY give performance, giving 90-95% of the 8700k's performance, but at barely half the CPU cost. ( 8700k is a beast, however)