As announced in Apache announce mailing list, JMeter 2.8 has been released last week. Take a look at http://jmeter.apache.org/changes.html for a complete list of changes in the current version.

Among the changes, the “Thread Group: New Option Delay thread creation until needed” has great impact over the execution of performance tests with many threads. Basically, instead of creating the whole thread pool before running your tests, now JMeter creates the threads as needed, avoiding unnecessary threads and saving a lot of memory.

Have fun! And kudos to the JMeter team!