We don't support third party images here and we definitely don't condone distributing RetroPie with pirated material in any way. That kind of activity is illegal and threatens the very existence of this and similar projects. Accordingly, the @Wolfanoz account has been banned.
It might be related to Debian Stretch, if the RetroPie image hasn't been correctly updated to Debian Stretch. I had this issue running OSMC Stretch with RetroSMC script. It used to work until Debian Stretch came out then it stuttered and was totally unplayable. Everything stuttered and slowed down drastically
Try this, it will update ALL your RetroPie cores and emulators to the latest Debian Stretch code. It compiles EVERYTHING from the source, which WILL take some considerable time. Leave it running overnight to compile and update ALL the code to the latest builds
Choose the following option, and be very patient. It WILL take hours and hours. Hence running overnight
Update All Installed Packages : This will update the RetroPie-Setup script and all installed packages
3rd party images are installed in a quick fashion with very little aftermarket support. You might be even better, as suggested, downloading a proper image and starting from scratch. At least then you know it WILL work correctly