Buffering happens when a show needs more data to stream smoothly than is available over your internet connection. Playback pauses as the Netflix app waits for the data to arrive on your device.  As a general rule, a VPN will slow down your internet connection — especially when connecting to a VPN server a long distance from you. If you have a slow internet connection to start with, this may cause buffering issues.However,  this slowdown is minimal with a good VPN service(especially if you use Proton VPN’s unique VPN Accelerator).