vCenter 5.1 Performance slow

[FJ1200]

just come back from a customer site where their vCenter 5.1 is running really slow.  Connect with vSphere client and RDP.  It's jerky, freezes and then frees up, but the CPU is running at about 10% and of 10GB memory it's only using 10%-25%.  The database is on a separate vHDD with acres of space. Datastore is an iSCSI LUN on a Dell MD3620i SAN with 35% free space.  Latency doesn't look bad, wait and ready states are low, network is 1Gbs to the switch and then 10GB to the SAN and between switches so plenty of room.  We're back on site again in a week or 2 and would like to resolve it if at all possible.   Any ideas as to where to look next?  There are 7 other vms on the same LUN and 18 other vms running off the SAN but at present the system isn't live so they are not doing much.

[raog]

1) How many vCPUs?

2) What is the size of the inventory VC is managing?

3) Do you notice any CPU/mem usage spikes?

Regards

Girish

[FJ1200]

2 vCPUs.

Occasional spikes - one hits 100% but few and far between.

Total inventory is 37 vms.