Compared to the top speed of USB 2.0, firewire 400 was actually faster in that regard (due to a consistent transfer rate rather than a variable one), and I’ll explain where the true performance came in to play, and how thunderbolt also has this amazing feature:

When usb connections begin to data transfer, they started at 0 Kb and slowly speed up to the maximum transfer rate. Then it slows down before completion. FireWire (and is successor, Thunderbolt) maintain a consistent data transfer speed. It begins at that transfer rate, and ends at that transfer rate. This is especially good if you’re moving around a large amount of small files.

Also, firewire 400 already beat out USB 2.0’s 382 Mb/s transfer rate. Firework 800 more than doubled it, and thunderbolt 1 started at 1.5 GB a second. We’re at thunderbolt 5 now, and I stopped keeping track of the data rates because they were so blazingly fast.

One drawback, however, is that firewire cables, and subsequently thunderbolt cables, are both extremely expensive and not very durable. They contain a lot more twisted copper wires, and tend to wear out faster. USB cables are nearly indestructible.

Additionally, firewire (and thunderbolt) are also a networking protocol. You can create an ad-hoc LAN just with firewire or thunderbolt cable cables. This is natively built into macOS, but, on Linux, it requires some sorcery to make it work. With a Mac, and an emergency, you can boot your Mac with a damaged hard to drive remote remotely from another functional Mac just by using a thunderbolt cable (or a firewire cable). It’s a neat trick, and has saved my ass more times than I can count.

One final awesome feature of thunderbolt 2+ is that a natively carries DisplayPort signals since switching to the USB 3 plug standard.