My iPhone personal hotspot network is really slow when I use it on my mac computer?

How can I make it faster? I'm connecting them via Wi-Fi. Will doing it through USB make it faster? How do I do it through a USB cable?

Slim chance, but it may be faster with USB. Reason being, when you have cellular device near a Wi-Fi-access point, there's always possibility of wireless interference. Using a USB cable can eliminate this. However, there's a slim chance that internet was slow cause of interference, or your phone's connection to the internet is not strong or fast enough for your needs.