Improve calculation speed for this worksheet with INDIRECT/FILTER functions

[GeneBF]

Hello, Im currently looking to improve the calculation speed of my worksheet either through formula optimization or alternative formulas (No complicated VBA or PQuery).

I have a workbook "File A" that contains Tabs "Main" and "01" through "19". "Main" Tab is an interface which includes dropdowns that functions as filters mainly which Tab from "01" through "19" to use, and further filter down each data on each specific tab. Furthermore there will be a workbook "Main File" that will then have a filter on which excel file to use ("File A", "File B", and so on...) on a sharepoint folder.

On "File A" tabs "01" through "19" - I have the following formula (attached below is for Minimum 'rate', other columns contains max, ave, mean, and data count). I've only use LET to lable each range as a handful of people will also edit this and not that familiar or comfortable with large formulas, so for easier understanding and tracking I've input it in LET Function. I also used BYROW to return an array and prevent other people from accidentally editing the formula and a lot of rows will be inserted in between so this also eliminates copy-pasting the formula. Filters set from H5, H6, H7, H9, K10, and K11 are linked on "Main" Tab. "Main" Tab will then pick up this values (Min, Max, Ave, Mean, Count) based on selected Tab on one of the filters.

=LET(
           ProjectFilter,$H$5,           AssetTypeFilter,$H$6,
           StageFilter,$H$7,              RateTypeFilter,$H$9,
           DateFrom,$K$10,             DateTo,$K$11,
           InflatedRates,$M$15:$CP$15,  ProjectDate,$M$11:$CP$11,
           ProjectRateType,$M$9:$CP$9, ProjectName,$M$5:$CP$5,
           ProjectAsset,$M$6:$CP$6,       ProjectStage,$M$7:$CP$7,

           Formula,

           BYROW($M$17:$CP$300,
                       LAMBDA(R,MINIFS(R,
                                          InflatedRates,"Inflated Rate",
                                          ProjectDate,">="&DateFrom,
                                          ProjectDate,"<="&DateTo,
                                          ProjectRateType,IF(RateTypeFilter="All","*","*"&RateTypeFilter&"*"),
                                          ProjectName,IF(ProjectFilter="All","*","*"&ProjectFilter&"*"),
                                          ProjectAsset,IF(AssetTypeFilter="All","*","*"&AssetTypeFilter&"*"),
                                          ProjectStage,IF(StageFilter="All","<>0",StageFilter)))),
IF(Formula=0,"",Formula))

On "File A" tabs "Main" Tab - I have this formula to pick up the values resulting on the formula above. Cell C5 contains the dropdown for Tab Filter.

=LET(
             inD,INDIRECT($C$5&"!D1:D500"),       inB,INDIRECT($C$5&"!B1:B500"),
             inJ,INDIRECT($C$5&"!J1:J500"),           inC,INDIRECT($C$5&"!C1:C500"),

IFS($E$6="ALL",(FILTER(inD,((LEFT(inB,1)="I")*(inJ<>"")))),
$E$7="All",(FILTER(inD,(NOT(ISERR(SEARCH("I."&RIGHT(XLOOKUP($E$6,inC,(inB)),1),inB,1))))*(inJ<>""))),
$E$8="All",(FILTER(inD,(NOT(ISERR(SEARCH("I."&RIGHT(XLOOKUP($E$7,inC,(inB)),3),inB,1))))*(inJ<>""))),
TRUE,(FILTER(inD,((inC=$E$8)*(inJ<>""))))))

This will be then picked up again by a Main Separate File that will contain a filter which chooses which file to be linked on with formula below

=LET(
          link,"'https://sharepoint-link-here/[",
          sector,Main!$D$5,
          filetype,".xlsb]",
         formula,INDIRECT(link&sector&filetype&"Main'!D16#"),

IF(OR(formula="",formula=0),"",formula))

Some of the ways I can think of are:
1. Have the formula be in "Main Tab" only instead of 01 through 19, having a long indirect formula on one tab, instead of having multiple long formulas on each tab.
2. Set the calculation to manual, and include a VBA code to only calculate the selected tab in filter instead of recalculating the whole sheet every time (??? not really sure about this, just a thought trial)

Any suggestions will be appreciated, thank you!