Does the Steam overlay hog resources?

Solution 1:

The separate process which handles the overlay is called GameOverlayUI.exe on Windows, and gameoverlayui on Mac. [Don't know yet for Linux.] If the overlay is disabled, or if the overlay does not recognize/support the game window, then the overlay process will not even be running.

The overlay can be disabled per-game or everywhere:

• For an individual game, select the game in Steam and go to Properties → General → Enable Steam Community In-Game. This option is not available for shortcuts to “non-Steam games”.

• For all of Steam, go to Settings (or Preferences on Mac) → In-Game → Enable Steam Community In-Game.