more of a linux question

I`m having a linux question, I know it is not the right place but I know for sure we have some linux gurus around.

I`m trying to figure out why a simple bash loop like (pseudocode) : while i < n do i=i+1 end for similar hardware is running in 30 seconds on RHEL7 servers but in 75 on RHEL6.

I did a perf tracing on each process and I can observe that sigprocmask function call is accountable for around 20% of time in RHEL6 while in RHEL7 is not even present.

THere are couple of other functions not present in RHEL7 but only in RHEL6 like: strcpy_ssse3 (3% of time) , and some functions which runs 3 times faster on RHEL7 like mbrtowc 9.5% in RHEL6 vs 3.5% in RHEL7

DO you guys think it is a matter of just a newer / faster kernel? maybe other libraries involved like glibc?