Issue #2307681 by cbr, Berdir, moshe weitzman: GetEntityTypeFromStaticClass - poor performance.

core/lib/Drupal/Core/Entity/Entity.php

core/lib/Drupal/Core/Entity/EntityManager.php

core/lib/Drupal/Core/Entity/EntityManagerInterface.php

core/lib/Drupal/Core/Entity/EntityType.php

core/lib/Drupal/Core/Entity/EntityTypeInterface.php

...l/Core/Entity/Exception/AmbiguousEntityClassException.php

core/modules/node/node.api.php

core/modules/node/node.module

core/modules/node/src/Access/NodeAddAccessCheck.php

core/modules/node/src/NodeAccessControlHandler.php

core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php

core/tests/Drupal/Tests/Core/Entity/EntityTypeTest.php

core/tests/Drupal/Tests/Core/Entity/EntityUnitTest.php