This Sandisk Extreme microSDXC UHS-1 game me a huge boost in storage performance over my last SD card. When I first bought my Surface Pro 4, I purchased an SD card based on capacity and not on write speed. At the time I only wanted some extra space to store pictures and set it to where some apps could install. What I didn't realize was that old microSD card crippled my performance and transfers and installs that went on the old card was horrible (20 MB/s write).
With this card, I'm getting about 75MB/s write speed. Almost 4x better. Steam updates that took over a minute or so now occur in 30 seconds or less. It was a pain cause the updates for that app seem to happen every time I log in and if a game need to update, I just wouldn't play the game that session. Now with the Sandisk Extreme, it's almost as fast as if I had installed it on the primary storage that came with the Surface Pro 4. I just wish I had upgraded sooner!