Count unique value from a date range with multiple criteria by vba

Dear Expert,
To find out unique value from a date range considering criteria now i am using below formula. But those formula is very difficult & much bigger, when i use this formula multiple time in my same sheet then sheet will go down with very slow speed & finally sheet is not workable smoothly, but i need to use this formula in my sheet so many time like 20/30 times. So need any other solution like VBA or customize formula or any other that will not much impacted to my sheet size or working speed.

Below is my formula & Attached file for your ref where i use this formula on c4 cell.

=SUM(IF((Sheet2!$T$3:$T$9921>=$A4)*(Sheet2!$T$3:$T$9921<=EOMONTH($A4,0)*(Sheet2!$S$3:$S$9921<>"")*(Sheet2!$A$3:$A$9921=$B$2)*(Sheet2!$W$3:$W$9921=$B$1)),1/COUNTIFS(Sheet2!$A$3:$A$9921,$B$2,Sheet2!$T$3:$T$9921,">="&$A4,Sheet2!$T$3:$T$9921,"<="&EOMONTH($A4,0),Sheet2!$S$3:$S$9921,"<>"&"",Sheet2!$I$3:$I$9921,Sheet2!$I$3:$I$9921),0))

Please help me in this regards

thanks wahid