query delay

I am running 10gr2 on 4 blades, everything is running much faster than on the old server ......except;  

Periodically simple queries will take between 1 - 2 minutes. Simple as in

SELECT * FROM small_table.  

This delay does not happen all the time. I do not think this is an index issue. I think this is a RAC wait issue.    

I will occasionally (maybe once a day) get some of the following:  

   Metrics "Global Cache Blocks Lost" is at 25

   Metrics "Database Time Spent Waiting (%)" is at 57.65708 for event class "Cluster"    

Can anyone think of a way to investigate this?  

Thanks  

Randy              

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