Regarding the question of being slow computer wise, one thing to confirm is if the car still has MCU1 or has been upgraded to MCU2. The response of the center screen for loading navigation routes, loading map tiles if using satellite view, etc., is much improved for the MCU2 versus MCU1. You can find the current costs and impacts for doing this on Tesla site at:
https://www.tesla.com/support/infotainment
I think the other key consideration for them purchasing a 2014 MS is whether the car has first generation autopilot capability. This was introduced in late 2014, so depending upon when during the year the car was built, this will be a big distinction.
Another consideration for them is how they intend to use the car. Many owners of early 85s have experienced supercharging speed to have been dramatically capped by Tesla. You can find tons of posts around this if you google things like Tesla batterygate. If the car is going to be used primarily for local driving with home charging, then this may not be a consideration and a 2014 MS can be a good low cost Model S.
Not sure what cars are going for in your local area, but honestly, 20K seems a little steep for what I'd consider paying for a 2014 MS85, especially if it does not have AP1 or the MCU2 upgrade. I have a mid-2016 MS90D, 75k miles, with MCU2 upgrade that I may be looking at selling around end of the year. Depending upon if I go with something like selling to Carvana vs. private party sale, it's likely about a $25k vehicle.
Best of luck to your friend in his decision making.
