Calculate Business Days in Oracle Service Cloud

Summary

Please show the best way to calculate business days in OSC

Content

Does anyone have a formula to calculate business days in OSC reports?  I want to calculate the difference between incidents.updated and incidents.created.  I am not able to use the Incidents Performance Table in this instance; however, I would like to avoid using this table in general because I already have 5 table joins in my existing report and including this would drastically slow down the report.  .  See https://cx.rightnow.com/app/answers/detail/a_id/2240/ for the examples that can be used - and this difference cannot be calculated in the Incidents Performance Table.