Cascading dropdowns and large lists

Question

I am using JavaScript, JQuery, and SPCascadeDropdowns out of SPServices (from CodePlex) in my NewForm.aspx and EditForm.aspx.

I have a "Site" lookup column, and when the site is selected, it cascades to an "Asset" lookup column with the assets in the Assets list that refer to the Site value selected.

This all works fine. However, the relationship list (Assets) has become large (15,000+ items). Not ideal, but it is what it is.

The problem arises when NewForm or EditForm is loaded and SharePoint initially loads all 15,000+ items into that drop down, then SPCascadeDropdowns filters it for the selected Site, down to about 20 items. The load of those 15,000+ items every time the form loads takes several seconds and users are complaining that its slow.

Has anyone come up with a way to make SharePoint not initially load all of the items into the drop down, which is then just going to be filtered anyway by SPCascadeDropdowns?

Edit: This is SharePoint 2013, on prem.

Answer 1

in your asset list index the column that you are filtering by in your cascade (any column that is used to cascade by) should help reduce the querying and speed things up for you:

about indexing:

https://support.office.com/en-us/article/Manage-large-lists-and-libraries-in-SharePoint-2013-and-SharePoint-2016-b8588dae-9387-48c2-9248-c24122f07c59

how to do it (its simple):

https://support.office.com/en-us/article/Manage-large-lists-and-libraries-in-SharePoint-2013-and-SharePoint-2016-b8588dae-9387-48c2-9248-c24122f07c59#__create_a_simple

you didn't state what version of sharepoint so im assuming 2013+ but the concept is the same for 2007 and 2010 (indexing is found in the list settings)