USB Flash Drive Recomendations
For those running pfSense on a USB flash drive. To ensure the best performance use a flash drive rated for ReadyBoost.
Installation, upgrade, etc. can be agonizingly slow on a USB flash drive not rated for ReadyBoost.
Readyboost is a windows term,
Yes it claims that it meets a certian speed requirement, but this day and age, just get a good branded device and call it good
USB 2.0 or USB 3.0,
just make sure it's not cheap big-box store brand, and you'll be fine
(FYI, i've converted almost all of my USB2 thumbdrives to USB3.0 - they are faster even on usb2 ports)