Are you using Smart Client and Windows SSO by any chance? Performance on server calls seems to be hampered by using Windows SSO - did a write up here: Using Windows SSO over a WAN? Possible performance degradation for Smart Client
Are you using Smart Client and Windows SSO by any chance? Performance on server calls seems to be hampered by using Windows SSO - did a write up here: Using Windows SSO over a WAN? Possible performance degradation for Smart Client