Considering that an old 80's Encom server probably had very little memory (512K was massive in those days), I suspect that we could store the entire population of Earth on one of todays modern typical servers.

However that doesn't mean they can all be active at the same time, and thats the trick. How much realtime memory would an 'active' user require. How much CPU processing power would it require.

We know the upgraded Flynn secret lab server could handle two active users, but I wonder how much resources they consumed.

For that matter, how much resources would an ISO require, there were many in there.

Do you think today's server farms, like Google's or Facebook's, could manage Earth's entire population? I'm not so sure.

The server was an Encom super-computer with two, 3-foot tall towers, and it's unknown what it's max memory capacity was. It was most likely custom upgraded by Flynn himself to have vastly more memory and a faster CPU power than any common large computer server for 1982/1983.

The level of ENCOM tech is significantly more advanced that what it is in actual real life. Remember in the original TRON (1982), Dillinger had a touch screen desk (there was NO touch-screen tech at all in 1982 in real life), and the first Shiva Laser digitizing system that could turn matter into energy and digital code and then re-materialize it (still not really possible yet), and the Space Paranoids arcade game was a full 3d polygonal first-person arcade game, in real life in 1982 that wasn't possible to actually do outside of basic non-shaded ray-trace and vector graphics.