I don’t know if the issue is in Retropie (the image) or the Pi itself.
I have other strang issues, like drops in SSH connections, and problems to reboot the Pi, it sais that it’s going to reboot, but nothing happens.
I’m having the same issue with ssh, but I’m using wifi and I read somewhere that the built-in wifi driver is having some issues on some OS flavors…maybe this one too. Are you using wifi and if so are you using the onboard wifi or a usb stick?
Have your tried the built-in wifi? If so, within 10min I can almost guarantee you’ll lose a ping or more especially if your CPU is busy. Though I did find that having too many devices plugged into the usb port exacerbates the issue, especially if you use a 10′ long usb extension cable like I do. Probably a power thing, my guess is if under med-high CPU load and a few peripherals (w/o external power) are plugged in it starts shutting down power to the wifi before anything else.
I’m working on finding or acquiring a powered usb hub (which I know is kind-of the golden rule with Pi’s) to see if that helps things along.