Tagging a test as 'large', means that the test class has the following characteristics:
it can executed in an isolated JVM (Tests can however be executed in different JVM on the
same machine simultaneously so be careful two concurrent tests end up fighting over ports or
other singular resources).
ideally, the whole large test-suite/class, no matter how many or how few test methods it has,
will run in last less than three minutes
No large test can take longer than ten minutes; it will be killed. See 'Integeration Tests'
if you need to run tests longer than this.