Halo's developers explain what can go wrong with unlocked framerates in old game ports

It’s also worth remembering that these kind of weird ass behaviors and bugs can occur on games  natively developed for PCs. Older games often have to cope with hardware that is faster than anyone imagined, and totally different from what the game was developed on.

A prime problem that comes to mind is the flying APC bug in MW3. On my older Pentium D machine, APCs would often fly up into the air and usually come back down. On my Core i5 machine: they never would come back down, or even be within targeting range most of the time. Which makes it hard to complete some of the early missions, lol. Today you require limiting the CPU speed and emulating a graphics card in software just to render it playable on modern hardware.

In fact, the game was old enough that when my eyes lit up at finding a copy of Mech Warrior 3: the next problem to solve was convincing the clerk to sell it to me because there was no returns welcomed, lol. I seem to recall Pentium 3s and Pentium IIs being high end processors around the time the game was released.