Spring start afresh for each test run

Each time I run tests using rails test, Spring starts up in a new instance. See below:

$ spring status
Spring is running:

56604 spring server | sample_app | started 9 mins ago   
56804 spring app    | sample_app | started 7 mins ago | test mode      

$ rails test
Running via Spring preloader in process 57248
Started with run options --seed 27813

  5/5: [=====================================================================================================================] 100% Time: 00:00:00, Time: 00:00:00

Finished in 0.58059s
5 tests, 9 assertions, 0 failures, 0 errors, 0 skips

Any way to prevent this to improve test suite performance?