I'm glad you could play again. The overlay offers quick access to Steam features without leaving the game, allowing you to chat with friends, check game guides, browse the web, or take screenshots easily.
Besides this, some games use the overlay for trading within Steam.
Another example is the NVIDIA Geforce Experience overlay, which is mainly for recording or tweaking graphics settings. If you don't use it, you can disable it too.
Disabling the overlay is like removing an extra load from your computer. Ultimately, it's about minimizing background processes while gaming to enhance your computer's performance.
If you need more help or have additional questions, I'm here to assist you :)
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