Migrating from Java Calendar to Joda Date Time

Previously, when I first design a stock application related software, I decide to use java.util.Date to represent date/time information of a stock.

Later, I realize most of the methods in java.util.Date is deprecated. Hence, very soon, I refactor all my code to make use of java.util.Calendar

However, there is 2 shortcomings I encounter.

1. Construct java.util.Calendar is comparative slower than java.util.Date
2. Within the accessors getCalendar method of Stock class, I need to clone a copy, as Calendar is a mutable class

Here is the current source code for Stock.java

Recently, I discover Joda-Time. I do the following benchmarking, by creating 1,000,000 java.util.Date, java.util.Calendar and org.joda.time.DateTime. I found org.joda.time.DateTime performs better than java.util.Calendar, during instantiation.

Here is the benchmarking result.

This instantiation speed is important, especially many instance of Stocks will be created, to represent a long price history of a stock.

Do you think is it worth to migrate from Java Calendar to Joda Date Time, to gain application speed performance? Is there any trap I need to pay attention to?