Prime number test

[Lucas]

I found:

Function IsPrimeNumber3

Code:

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function int'n

if(n=1) ret 0
if(n<4) ret 1
if(n%2=0) ret 0
if(n<9) ret 1
if(n%3=0) ret 0
int r=sqrt(n)
int f=5
;bucle
if(f<=r)
,if((n%f)=0) ret 0
,if(n%(f+2)=0) ret 0
,f+6
,goto bucle
ret 1

Do you know why IsPrimeNumber3 is slower than IsPrimeNumber2?