Array formula working too slow

Hello,

I am struggling with a formula, which works OK, but is not efficient for the large amount of data stored in the Excel sheet. The table I am using have thousands of rows and the workbook becomes very slow because of the calculations.

I was wondering if the formula I am using can be changed or modify to make it quicker. Maybe a macro will do the job as well.

I have attached a small version of the table where I have the formula. Columns in red have the formulas which I am explaining.

Hope someone can give me an idea about this. Any help would be much appreciated.

Thanks & Regards