With Sage 2020 and Sage 2021, my clients that have larger inventory (5000 items or more) are having major problems with Sales Orders, Purchase Orders and Sales Invoices when attempting to enter transactions with the Drop Down List and Automatic Field Completion enabled (with Windows 10 computers). The "lookup" time to locate the items is about 10x slower on Windows 10 than Windows 7 computers.

Note that the same clients on the same network still running Windows 7 have no issues.  

Please do not send references re: network environment, as I can confirm this issue running on single standalone computers as well. 

It is an issue with Windows 10 and how it treats automatic field completion and drop down list.  (Turning off these features is NOT AN OPTION - when clients have 6k or more of inventory items)