Optimise for ad-hoc is turned on on this server already - but there is still a lot of single use plans in the cache - presumably these have all been run twice so the second time the plan is persisted

CacheType Total Plans Total MBs Avg Use Count Total MBs - USE Count 1 Total Plans - USE Count 1

Proc 13721 3105.820312 31 842.914062 3282

Prepared 14232 1502.687500 13 569.960937 4502

Trigger 559 288.375000 12 91.898437 150

Adhoc 2972 100.975097 5 46.225097 2035

UsrTab 384 15.390625 56 0.523437 12

Check 14 0.484375 2 0.187500 5

View 1957 206.054687 3 0.000000 0

I'll keep an eye on the memory and if it looks like it's having issues then I'll tune back the max memory setting but for the time being I think it looks like it might be ok.

Thanks heaps for your advice Jonathan - very much appreciated.