The Legend of Zelda: Breath of the Wild received an update last week that improved framerate performance on the Nintendo Switch version of the game. This update was also applied to the Wii U version, however, after Digital Foundry conducted a few tests, it was found that the Wii U version may need another coat of paint.
Two areas where the game originally suffered from some heavy frame drops, Kakariko Village and Korok Forest, was nicely smoothed over on Switch, but the Wii U version seems to still have this problem.
Some of the update fixes the game's performance, but the changes are much less noticeable on the last-gen version. Being the last first-party game designed on Wii U, this isn't entirely surprising. The Switch version of the game is clearly the optimal version of the game, but with Switch shortages expected throughout the year, this version isn't accessible to many.