In our environment we have vCSA 6.5.0 U2G 13638625 with 100 ESXi host and around 600 VMs. Webclient is running too slow and gives timeout errors (See attached) while trying to pull out any inventory details such as datastores, performance charges, VMs running on the datastores etc. The refresh sign keep spinning and then it results in query timeout errors. This issue is recurring after very 2 to 2.5 months. As a workaround, we planned a reboot every 2 months and it was working as after reboot of appliance, webclient performance seems to be better for few days. But, this time even after rebooting, it is giving same issue. The query time out errors are very annoying and end users are unable to work properly due to this.
Raised a support case with VMware and they tried to increase the memory size of vmware-vpxd-svcs and vsphere-client service to 2048 but it didnt resolve the problem. Any suggestions on this ? Has it got something to with this - We still have previous vCSA 6.0 appliance server in powered off mode in this inventory. (Just considering) or anything else. We take a daily clone of appliance but we stopped that also in order to check, but it didn't work out. 
