Switch isn't the best performer here it's the ps4 in its 6th year. Yes 6th year
But by the looks of it, this will be one of the last times it can achieve that, needing both critically acclaimed releases and a pricecut in japan to edge out a Switch without anything notable at all. Still, it's doing great for it's age.
One Super Mario Maker 2 rolls out and the slew of summer/fall releases start boosting Switch sales, I don't think the PS4 will be able to pass the Switch anytime again unless with some very big release (like a TLOU for instance) at a slower week for the Switch.
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454