@i_tye you also didn't say much about your Laptop make/model/
age. USB ports have been around a LONG time and have a number of generational improvements from USB 1 to USB 2 to USB 3 to USB 3.1 to USB 3.2....
USB 3 can be in the ballpark of 5Gbps to 20/40 Gbps on thunderbolt.
USB 2 maxes out around 480 Mbps (at least 1/10th of USB 3)
USB 1 (really, really old) was like 12 Mbps
With anything video it depends on your resolution, framerate and compression settings. 4k is 400% the data of HD. 60fps is 200% the data of 30fps. Plus your codec/compression settings will impact filesizes/bitrates.
Obviously there is a "spectrum" of possibilities and not one right answer. The higher of a resolution and framerate you have chosen, the better hardware you will need. New laptop with USB 3+ with a higher end SSD external harddrive for lower latency. The lower you are willing to go on resolution and framerate the older of a computer/usb/harddrive you can get away with.
Lots of cheap external harddrives you find at "big box stores" will be spinning 5400rpm mechanical hard drives. These are relatively slow (but also relatively cheap for the size). You can then upgrade to 7200rpm spinning drives and then the serious video pros will want solid state drives (SSD) for the speed (but they cost a lot more too).
Last but not least: USB is a shared pipe for data. So if you have your external hard drive plugged into a USB hub (some laptops will have an internal hub exposing 2+ ports externally that are actually shared total bandwidth) then other devices on the same USB controller can cause a "hiccup" in the transmission speed. For example if you have your webcam and a harddrive sharing a USB controller, it may be less performant as they are sharing USB bandwidth. Again a higher end laptop will have more dedicated USB ports, and a lower end one might have more shared USB ports.