Useful trick to stop Excel from calculating formula when not needed.
Turn Off Automatic Calculations
Application.Calculation = xlManual
Turn Automatic Calculations Back On
To turn on automatic calculation from VBA:
Application.Calculation = xlAutomatic
Manual Calculation
To force Excel to recalculate:
Calculate
Recalculate an individual worksheet:
Worksheets("Sheet1").Calculate
Source
https://www.automateexcel.com/vba/on-off-calculations/