While the Nintendo Switch is no doubt powerful for a portable system, there have been some issues with framerate drops in certain games. While many, including myself, thought these issues were due to the Nintendo Switch's somewhat modest specs in comparison to its peers, a third-party developer informed Nintendo Life it may be connected to a known issue with the Switch's Wi-Fi connection which places additional load on the system's GPU.
The Legend of Zelda: Breath of the Wild, in particular, was affected by stuttering and slowdown. Zelda isn't the only Nintendo Switch game affected by graphical maladies though. Fast RMX suffers from resolution drops from time to time, and I Am Setsuna is affected by frame rate fluctuations in addition to being locked to 30fps.
Tests by users have shown that by turning off the Wi-Fi auto connect option in the Nintendo Switch System Settings, many framerate issues seem to be resolved. It seems that scanning and attempting to connect to Wi-Fi periodically puts a load on the CPU which causes framerate and resolution issues in certain games. When the auto-connect option is turned off, the users stated that the graphical issues were gone in Fast RMX and I Am Setsuna, and minimized in The Legend of Zelda: Breath of the Wild.
Whether this is a placebo effect or not hasn't been thoroughly tested. However, Nintendo Life claims that developers confirmed that Nintendo is aware of the Wi-Fi issue and that an upcoming firmware update would patch the problem.