> Would a USB3 external drive help with this?

Emphatically yes. It's an entirely different experience using a RPi 4 with a quality SSD. [0] It's also more expensive, so you have to decide whether that's important to you.

[0] https://www.samsung.com/us/computing/memory-storage/portable...

In my opinion it's a mistake to split the difference with a cheap SSD or one you need to plug in using a SATA to USB adapter. (troubleshooting first step: if it's not the power supply, it's the SATA to USB adapter...)