Terrible! Once that microSD card is more than half full (let's say almost 2/3 full), the performance of that microSD card is just disgusting. kb/s instead of mb/s. Below is an image of a performance test I just ran with an SD card. In principle, no operating system can save, read/write data. I will return this item as soon as possible. Some people will say it might just be my computer. I tested this on 4 different PCs. All had the same results.
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