Performance issue in OIM during Exchange Target Resource User Reconciliation job execution

We are getting Out if memory issue in OIM  during "Exchange Target Resource User Reconciliation"  recon job execution. OIM has reconciled users from Trusted Resource and provisioned into Active Directly which internally created mail ids in Exchange Server. After this, Exchange Target Resource User Reconciliation job has to execute and populate email ids for the users in OIM. During this process, this job is getting all the users from AD and comparing with OIM for the available users in OIM to update email IDs. For example, if AD has 30000 users and OIM has 1000 users, it is getting all