PROBLEM
In ArcMap, when using the Measure tool in a snapping-enabled environment to measure the features of a large shapefile, the tool exhibits a slow performance and the application freezes. Disabling snapping allows the Measure tool to function normally, but it is not a viable solution when conducting measurements, as snapping enables accurate measurements of the features.
Note: Working in ArcGIS Pro with the same shapefile and snapping enabled, exhibits a different behavior compared to working in ArcMap. The application does not freeze, but the snapping function does not work when moving the cursor among the features to measure, even though it is turned on.
A possible cause of the issue is the shapefile does not have a spatial index, thus slowing the snapping of features when using the Measure tool. ArcMap requires a spatial index to quickly identify or locate a feature, selecting features by pointing or dragging a box, and panning and zooming. A spatial index is not always automatically created in a shapefile, as it is for a geodatabase feature class.
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