u/20260819

to be specific i'm writing a cpu-based rasterizer. the maths are not difficult but i find a strange property: if i divide the procedure into some small functions, the code looks cleaner and is easier to maintain but a bit slower. on the contrary if i put everything into a single procedure, it looks stupid but fast. why is that? an example illustrating this

code 1:

if cross_product(x0,y0,x1,y1)>0 then zzz

(and i write a "cross_product" function separately)

code 2:

c=x0y1-y0x1

if c>0 then zzz

code 3:

if x0y1-y0x1>0 then zzz

if i write the entire algorithm in the style of "code 3", it runs the fastest. "code 1" is slowest

is it normal?