vCenter web Client 5.5 fails to log in or takes lot of time (around 10 -20mins)

Hi,

We have the 3 vCenters (5.5) which is connected with Linked mode, it's taking lot of time to login to the server or sometimes it fails with

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Unable to connect to vCenter Inventory service on "VCName"

I checked the  - vmware-sts-idmd logs and found many many errors like below

2015-05-06 12:19:46,351 INFO   [IdentityManager] Failed to find group [xxxx] as FSP group in tenant [vsphere.local]

2015-05-06 12:19:46,453 INFO   [IdentityManager] Failed to find group [xxxx] as FSP group in tenant [vsphere.local]

2015-05-06 12:19:46,556 INFO   [IdentityManager] Failed to find group [xxxxx] as FSP group in tenant [vsphere.local]

2015-05-06 12:19:46,658 INFO   [IdentityManager] Failed to find group [xxxx] as FSP group in tenant [vsphere.local]

Any suggestion to resolve the issue?

As a workaround, we need to restart vcenter Inventory service (mostly all vcenter service)