hello dear forum members and admins,

if you help me to solve the issue, I would appreciate thanks in advance

i created a dashboard to calculate customer numbers based on raw data prepared on day and time set.

there is no problem here. but I also want to calculate the monthly average customer numbers based on the time set. for this purpose, I created a data table in daily_pax_details sheet. for e.g in January between 10:00 - 10:30 CUSTOMERS E totally number is 35 and this 35 amount occurred in 8 days, then it calculates 4 amounts in cell K137. but in some cases, raw data include more than 20k line and its calculating and waiting too much. is there any other way to do it in a quick way ? I am so thankful, attached file is uploaded