Finally I did the test on a 16F887 at 8MHz, and came up with a 49 usec to enter ISR and around 45 to exit.
The code I used is this:
wsave var byte $70 system
wsave1 var byte...
My god ! I am looking to my shoes now ...
I don't know the English exact term ..
It is super to deal with guy like you
I will try ..