Performance for the NPC web service can be improved by setting up the Portal Web Service with its own application pool.
If for example the same data loads just fine at the NV or RA console that would point to a possible problem with the NPC web service and this should help.
Add another IIS Application Pool for the NPC PortalWebService.
Server Manager > Roles > Web Server (IIS) > Internet Information Server > in the middle expand the server name > Application Pools > right click Add Application Pool >
Name: PortalWebService
.NET Framework version: .NET Framework v2.0.50727
Managed pipeline mode: Classic
Start application pool immediately should be checked.
Now expand Sites > PortalWebService > Advanced Settings > select Application Pool > on the right end where it shows 'npc' click the '...' > in the drop down list for Application Pool select PortalWebService.
Open a command window and enter 'iisreset'.
Note, the NPC SP2 upgrade will set the PortalWebService back to using the NPC application pool so after the upgrade it is necessary to manually point PortalWebService to use its application pool.