Performance Tools | Unreal Engine 4.27 Documentation

FPS: Shows the frames per second, as well as the current delta time (time between each frame).
Mem: Shows the current amount of memory in use by the engine.
Objs: Shows the current number of objects in the scene.

At the top of the Level Editor window, at the right side of the Tab Bar, you will find a series of performance and debugging tools.

From left to right, they are:

Number	Name	Description
1	Console Command Bar	This text field is used to input console commands within the editor.
2	Source Control Status	This shows the current status of the integrated Perforce server.
3	Performance Data	This region displays the following information: FPS: Shows the frames per second, as well as the current delta time (time between each frame). Mem: Shows the current amount of memory in use by the engine. Objs: Shows the current number of objects in the scene.
4	20 Second Playback	This saves a 20-second video of the last 20 seconds of work. A bar will appear at the bottom of the Level Editor showing the path to the video.