When using the Add Data button in ArcMap, browsing and loading data from a network server takes a long time.
This problem is related to virus protection software.
Solution or Workaround
To browse and add data to ArcMap from a network server at a faster rate, disable 'online virus protection' within McAfee Anti-Virus software. This has also been found in Symantec version 10.0.1.1007.