things making bapi faster than bdc

Hello Friends,

I am thankful to you if any one can clarify my doubts.....

Can any one let me know ...... that.

BAPI is faster than BDC... that i know.

what my question is ...

if suppose BDC takes 30 minutes to update..

and let BAPI for that perticular Transaction takes 15 minutes.....

Let 5 minutes times for screen processing...

Where the other 10 minutes difference is effecting...

& please let me know..... what are the other factors effecting the performance between

the BAPI & BDC.

in advance Thanks to all...

regards,

Phaneendra P.