@puspa
Depends on so many factors like how big the database is, how large some of the tables are (ie. size and amount of records), if your server/database server is slow, if your database is not optimized, etc. So there is no telling unless you have detailed logging enabled.
If you upgraded from 1.10.x then you had a lot of database patches that needed to run and one or more of them is pretty hefty like updating the thread_entry_email table, etc.
Cheers.