For fast speed, the cards should be at least UHS class 3 (U3). Class 10 or U1 cards can be slow and lead to long loading times. The speed numbers given are always maximum numbers and provide zero information how fast the card really is.
U1 cards can be slow, I recently bought a 128GB card for my phone and it is unusable. Apps take up to 10 seconds to start.
U1 cards can be slow, I recently bought a 128GB card for my phone and it is unusable. Apps take up to 10 seconds to start.