DB Design :: Insert / Update FACT Table From Staging Table

We need to Insert/Update a Fact Table from staging Table. currently we are using a SP which update Fact Table for Each region.  this process is schedule,  every 5 min job is run and Update fact table.but time of Insert and Update too long from  staging  to Fact, currently we are using merge statement for Insert and update.in my sp we are looping number  how many region we need to update and at a time single Region we are updating using while loop in current SP.