Install Gladys on an SSD instead of a micro-SD

Configuration
8

I’m not sure it’s only due to the SSD, since you wrote just before that there is cache that may have biased your results ^^

I’m not sure, however, that your commands were correct, I advise you to do as in this tutorial: Your Web Host Doesn’t Want You To Read This: Benchmark Your VPS

To test write performance:

dd if=/dev/zero of=diskbench bs=1M count=1024 conv=fdatasync

Then you clear the cache:

echo 3 | sudo tee /proc/sys/vm/drop_caches

And finally you test in read:

dd if=diskbench of=/dev/null bs=1M count=1024

Can you tell us after that?