Improve pytest ergonomics

1. Disable perf tests by default
2. Add instruction to run tests in parallel

pytest.ini

@@ -5,6 +5,7 @@ filterwarnings =
     ignore:record_property is incompatible with junit_family:pytest.PytestWarning
 addopts =
     -m 'not remote_cluster'
+    --ignore=test_runner/performance
 markers =
     remote_cluster
 testpaths =

test_runner/README.md

@@ -56,6 +56,14 @@ If you want to run all tests that have the string "bench" in their names:
 
 `./scripts/pytest -k bench`
 
+To run tests in parellel we utilize `pytest-xdist` plugin. By default everything runs single threaded. Number of workers can be specified with `-n` argument:
+
+`./scripts/pytest -n4`
+
+By default performance tests are excluded. To run them explicitly pass performance tests selection to the script:
+
+`./scripts/pytest test_runner/performance`
+
 Useful environment variables:
 
 `NEON_BIN`: The directory where neon binaries can be found.