Hibernate performance

In one hibenate project
We are having performance issue
Like if in one screen we have to highlight the car booked times per day am/pm wise for 3 months
For each booking we are updating one row in db like today from 10 am to 11 pm like.
So in screen am or pm section gets color highlight .like this for three months it will show.

In java using hibernate we are getting data for each am or pm (based or data) of day and storing in hashmap .
Hashmap key is amday value is am if pmday is pm.

This piece of code is working fine incase of less records .If many cars are booked in each day then it is taking too much time.so we will get irritation.

Problem only when we try to get all 3 months data to show in screen .So while screen load for view it is not at all loading if many rows are there .It is executing.......

So solutions are welcome .Thanks in advance