Thanks Dapi, Hrishi for help.

Dapi is correct, It's really elapsed time for taking snap. Really too long compared to Dapi's few seconds.

I analyzed my perfstat schema (which was not analyzed before )
Now it takes some 5 Min to execute the snap. Which also I think is too much.

Dapi, please tell me how to "take the proc apart and try running it query by query till you find the slow one."

Because I am executing by following way

SQL> execute statspack.snap;


Tuning of the performance tuning tool (Interesting isn't it ?)