tammerwhisk: Calculating delta time and what not is not nearly as straight-forward as just locking everything to a certain framerate.
Not to mention more expensive instruction-wise.
Having worked with the lowest level instructions, on x86 hardware the basic instructions (
add, subtract, xor, etc) are probably 2-5 cycles, while multiply is about 40 and divide can be a whopping 160! That was for 32bit instructions, 64bit could be slower.
Since most detla frames are also going to be in floating point, you are heavily going to be relying on multiplication of that value. Multiplying everything against the delta vs just adding a fixed number can be quite the strain when there's hundreds of thousands or millions of calculations done for that.
Fixed framerates sound better in my mind, but they have to be high enough that it's not an issue. Say pushing for 120 frames, with a second piece of code compiled for 60, then you get the advantage of pure raw speed in the instructions and code while also getting high framerate results.
But that's not how most 3D games are written. One second you could have 60, dip to 55, or go just over 60... sounds like a mess.