If you are working with a Bugzilla 4.2 server, where data is actively modified (there are many changes), it is recommended to explicitly specify the server time zone in Deskzilla. Otherwise Deskzilla might be downloading more information than necessary during synchronization (depending on the server time zone).
The synchronization mechanism works this way to make sure all the latest changes are downloaded. But if Deskzilla doesn't know the server time zone, there might be a big time overlap which will add some serious performance penalty.
To let Deskzilla know the server time zone, please go to Tools | System Properties and add bugzilla.request.date.zone parameter with the value in the following format: GMT-XXXX or GMT+XXXX.
For example for PDT it will be GMT-0700.
You can check the server time zone next to any time value, when checking it through the web.