Using Rhino 7.3.21348.1300 it can still freeze for what may be a few second to over a minute when the option to snap to mesh vertices is on and your mouse cursor hovers over the area of the screen with a large cluster of mesh vertices.
If possible it would be great for this not to happen.
I don’t know if it would help with this particular issue, but you might want to update Rhino to the latest release, 7.14 - lot of water under the bridge since 7.3