What will happen if you played a PC Game on a PC that only meet the minimum requirement and not the recommend one?

These are all my personal experiences example and they from my past and I only have two example because it only happen twice for me.
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Game: Star Trek: Voyager – Elite Force
OS: Windows 98

Resulting Problem: Long Loading Time
My Comment: The game itself run smoothly but when it time to load to the next section or map that require loading screen. It took from 15 minute to more then an Hours to load, depend. Years later when I play this again on a newer OS, it only took less then a minute to load.

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Game: Tom Clancy's Endwar
OS: Windows XP

Resulting Problem: Lag (on single-player)
My Comment: It lag plain and simple. This force me buy and install a graphic card on to the computer. After the new graphic card is up and running, the game run smoothly.