Replace formulas that are slowing down Excel model significantly

Could you help me rewrite the formulas in the attached that are slowing down the calculation of my model significantly? The formulas in question are highlighted yellow on the (3) Help tabs in red (columns are AR, AS and AV). The yellow tabs are the lookup tables that the formulas on the Help tabs reference. These lookup tables are thousands of rows long. Also the formulas on the Help tabs are also thousands of rows long and are repeated many times on each tab referencing multiple years of data, which is why the calculation time of the model is now 12 seconds any time something changes.