About response time of MFXInit()

I use IntelMSDK 2018R1 and software decode.

I have problem with Intel Core Processor i7-8700 when I do MFXInit().

i7-8700 is later than i5-3xxx in response time.

i5-3xxx is later than Pentium E5700 in response time.

i7-8700:220mS、E5700:20mS.

I need to frequent init and close, and create many session.

but, i7-8700 is later than old cpu in init response time.

Why?

I expected  i7-8700 is faster than old cpu in init response time.

Is there any workaround?

Thanks,