My Toshiba SD card says it's too slow after I format it in my Android cell phone

Mar 12, 2018
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I format my Toshiba SD card to use in my ZTE BLUE MAXX and after I do I get a message telling me that my SD card is slow and that continuing to use it will show down everything in my phone. How can I "speed it up" so I can use the crap out of it?