Derick recently committed a patch that improves the performance of code coverage data collection in Xdebug.

Xdebug 2.0.0:

  Workflow:
    ezcWorkflowDefinitionStorageXmlTest:    ..............................................
    ezcWorkflowExecutionTest:               .................................................
    ezcWorkflowTest:                        .....................
    ezcWorkflowNodeTest:                    .....................
    ezcWorkflowConditionTest:               .........................
    ezcWorkflowVisitorVisualizationTest:    .................
  WorkflowDatabaseTiein:
    ezcWorkflowDatabaseTieinDefinitionTest: ..............
    ezcWorkflowDatabaseTieinExecutionTest:  ....
  WorkflowEventLogTiein:
    ezcWorkflowEventLogTieinListenerTest:   ......................

Time: 02:15


OK (219 tests)

Xdebug 2.0.1-dev:

  Workflow:
    ezcWorkflowDefinitionStorageXmlTest:    ..............................................
    ezcWorkflowExecutionTest:               .................................................
    ezcWorkflowTest:                        .....................
    ezcWorkflowNodeTest:                    .....................
    ezcWorkflowConditionTest:               .........................
    ezcWorkflowVisitorVisualizationTest:    .................
  WorkflowDatabaseTiein:
    ezcWorkflowDatabaseTieinDefinitionTest: ..............
    ezcWorkflowDatabaseTieinExecutionTest:  ....
  WorkflowEventLogTiein:
    ezcWorkflowEventLogTieinListenerTest:   ......................

Time: 12 seconds


OK (219 tests)

This makes PHPUnit's code coverage functionality so much more practical to use.

Update: Xdebug 2.0.1 has been released.