If the delay happens when you select File->Open then mass compiling is not likely to do anything. The only thing that would do is to find VIs that are calling a subVI directly from the old network drive (something you should never do in the first place). This would give you the opportunity to relink to the new location.
I'm not sure which "file history" you might be referring to. There's the search path for VIs. Did you change it from the default to explicitly include the network drive? If so, you would need to remove this from the list of search paths. You can also manually check the LabVIEW.ini file to see if there are any other references to the old network drive.
Are you sure this is not a generic OS issue in terms of your recent documents, or something? Does it happen only with LabVIEW?
