you are much better off doing nthe actual printing from an sd card.
So no actual second computer needed :-)

If you use openscad for design - any machine will do it.

I'm currently using an amd Athlon 300g and 16gb ddr4 (overkill - but I wanted dual channel for the console emulatiors I play)
Basically openscad speed is dependant on single core clock speed and to get a significant speed boost over my £45 apu I'd ned to spend around £200. And even then it would on;ly sped up rendering by about 20%.
Given that it's now 5x faster than my previous workshop computer - I'm happy.

But yeah basically any machine will design and slice.

Printing from sd card or usb stick (depends on machine) is faster, more reliable and easier than pissing about trying to print over usb - windows 10 is not great at that and I find that the usb ports get reset during any print over about 10 minutes.
Usb is useful while dialling in settings - but no use at all for actual proper useage.

Also if you still want to go down the usb route - get a raspberry pi 3 or 4 and use octoprint :-)