NVMe vs SD Performance

I have a RockPi 4C+ with a 2Tb NMVe , using it to run jobs on mySql. I understand booting from the NVME is much faster, however, is the performance after booting also faster ? And if I switch to booting from the NVMe, is that reversible if I want to switch back to booting from the SD?

Thanks

Try it out. But first:
Back up your SD card to your Windows machine.

And follow my guide to nvme boot. It will wipe your rootfs partition off the SD card.