In a RAC environment the buffer cache is global across all instances in the cluster and hence the processing differs.The most common wait events related to this are gc cr request and gc buffer busy
GC CR request :the time it takes to retrieve the data from the remote cache
Reason: RAC Traffic Using Slow Connection or Inefficient queries (poorly tuned queries will increase the amount of data blocks requested by an Oracle session. The more blocks requested typically means the more often a block will need to be read from a remote instance via the interconnect.)
GC BUFFER BUSY: It is the time the remote instance locally spends accessing the requested data block.