Phil Webb opened SPR-12224 and commented

The MapPropertySource.containsProperty() method is not currently implemented directly, instead the EnumerablePropertySource implementation is used. This means for each containsProperty() call map keys are converted to an array then iterated.

We can improve performance by looking in the map directly.

Affects: 4.1 GA

Referenced from: commits 587a816, e71fbb9, 752574d, 65cc57d