Well, it looks like there might be a logical reason for this.
According to the third-party Nintendo Switch developer, it appears that the console’s Wi-Fi connection places additional load on the processor. It’s said that this will be fixed with a future system update.
Digital Foundry noted in their recently analysis that the framerate issues in Zelda: Breath of the Wild seemed to happen randomly and not in certain situations, which definitely leads us to believe that this does seem to be the issue.
It’s possible to enable Flight Mode to disable to wireless connection, but only in portable mode. This option is not available in TV mode.