Increasing write speed to MicroSD on MacbookPro
Indicated write/read speeds are always higher than what you should expect from a card.

Usually, the filesystem doesn't make a difference to the RW speeds.

Do also remember that copying many small files is significantly slower than copying one big file due to the entries required to the FS.

If you'd like to test your write speeds with the filesystem, try

dd if=/dev/zero | pv -betrP -s 100M -S | dd of=/path/to/your/device/temporaryfile 


The above command will dd 100 mebibytes of zeros into a file into your microSD card, and will return a speed in MiB/s.