How to imporve the performance of the Searching on "Completely Shipped" in sales order list?

Hi Expert.

Recently our customers feed back us a pb when they searching on "Completely Shipped" in Sales order list page, is very slowly , nearly 30 Seconds. I checked the count of records  just have 138701。How to fixed it ?

This field is a flowfield , which formula : 

Min("Sales Line"."Completely Shipped" WHERE (Document Type=FIELD(Document Type),Document No.=FIELD(No.),Type=FILTER(<>' '),Location Code=FIELD(Location Filter)))

I add a key "Document Type, Document No., Type,Location code " into sales line  , seems not work.

And I tried add a SIFT, "Completely Shipped" based on "Document Type, Document No., Type,Location code " , not work neither.

Any suggestion will be warmly appreciated.

BTW, My Version is Navision 2016.