4.91 SP4 client is slow when opening application located on Netware volume

Workstations were upgraded from 4.91 SP3 to 4.91 SP4 (or later).  After the upgrade, the time it took to open an application increased by 75%.  When the client was returned to SP3 the problem went away.  When Symantec client virus scanning of the network shares was disabled, the problem went away.

This issue is caused by the workstation Symantec client active virus scanning of Network shares.  Packet traces show that DLL/EXE read requests drop to 256/512 byte chunks from 4096 chunks when the 4.91 SP4 and 5 clients is used.  For example, opening an application with a 4.91 SP3 client generates 1874 NCP packets when starting a simple application.  When the client is upgraded to 4.91 SP4 or later, opening the same application generates 8308 NCP packets. 

The reason for the change after SP3 is due to Bug 213531 

Symantec Anti virus real time protection does not scan files on Netware

volumes.

Currently, the only way to resolve this issue is to change the default Symantec settings to not scan network shares.