Answer:   The disadvantages of using session are:
o Performance overhead occurs in case of large number of users, because session data is stored in server memory.
o Overhead involved in serializing and De-Serializing session Data. Because In case of StateServer and SQLServer session mode we need to serialize the object before store.

Answer:   Following are the disadvantages of using Session -

1. Performance overhead in case of large volumes of data/user, because session data is stored in server memory.

2. Overhead involved in serializing and de-serializing session data, because in case of StateServer and SQLServer session modes, we need to serialize the objects before storing them.