A friend and I each bought 387's (which was physically, a separate chip) for our 386's circa 1992. IIRC, I had a 80386/25 MHz with 4 MB of ram.

I remember a tank game called Scorched Earth where you would have to set angle & power to try to hit the other person's tank. Some ordinances took a 10-15 seconds to fire & complete because it was running FP ops on the CPU. Once the 387 was installed, this calculation was done almost instantly. That's about all I remember my FPU being good for. LOL good times!