Officially at Sage, and I was there for this, mapped drives were no longer required since a version 4.20 product update. That's when Vista support for MAS came along and UNC had to be supported as part of a Microsoft requirements for developers supporting Vista. Vista is a thing of the past but UNC is still fine.
However I have seen twice where loading a screen like S/O Entry in MAS 90 (Sage 100 Std) was taking 10 - 15 seconds and all the standard culprits like A/V, switch, etc were not in play. It turned out these networks had DNS issues and so executing a UNC path was resolving to the IP very slowly ergo the slow screen load. Experimented with a mapped drive and it was fast. It was easier to change the shortcut than trying to explain the issue. This is just the exception scenario of course.