The CrystalDiskMark bench of my Forma is as follows:
In real world transfers, I'm lucky to hit 2MB/s writes to my Forma.
My mum's Libra is the same.
I'm wondering if it's an issue with the vfat partition. Windows 10 isn't happy when I plug them in, says there's an issue with the drive, although I never have any errors or problems other than the slow transfer speed.