Why is does the first test ran with Robolectric taking so long?

I'm testing my Android app with Robolectric but I faced a weird situation. What happens is that when I run some set of tests, the first test ran with Robolectric takes much more time than any other test. It is not specific from the test itself, since I tried different configurations on the order of the tests and the result is that the first test is always the slowest.

Is it any robolectric setup time or something like that? Anyone knows about this?

Example here: http://ift.tt/1AEuqKZ

Thank you!