Any particular Amiga applications which greatly benefited from an FPU?
Any program that uses floating point math extensively should greatly benefit. It can be done automatically by going through an external library that uses the FPU if available, but this has higher overhead than inlined FPU instructions.
In general if a program has different versions for FPU and non-FPU, or the documentation states that it requires an FPU, then it probably has inline FPU code. Since requiring an FPU greatly reduces the target audience it suggests the developers thought the performance gain was worth it.
I was always curious exactly how much performance benefit did it
actually give. Are there any benchmarks or notable examples on the
Amiga where this difference is visible?
The benchmarking program AIBB includes several tests that show the difference between using software floating point math and inline FPU instructions. On my A1200 with Blizzard 1230-IV accelerator (50MHz 68030 and 68882) the following results were obtained:-
Savage (nested calls to transcendental functions in double precision floating point math):-
SC Math: 64.6 seconds
CP math: 1.68 seconds
speedup: 38.5 times faster
BeachBall (raytraced 3D beach ball rendered on hires 8 color screen):-
SC Math: 60.45 seconds
CP Math: 7.35 seconds
speedup: 8.2 times faster
The BeachBall test is probably more representative of typical real world performance (though of course results are always dependent on the particular implementation). In this case the speedup is equivalent to running the 68030 at 410 MHz, and 52% faster than a 50 MHz 68060 running software floating point code.