With Windows 10 1903, Microsoft had Insiders test a new Windows Search setting called "Enhanced Mode," which is designed to expand a search. Windows Search automatically indexes users' documents, pictures, videos and desktop (to conserve computing resources, Microsoft says). Users do have the option of customizing search locations manually or by clicking on Enhanced Mode to automatically expand indexing across all folders and drives.
However, testers found that the new search capabilities often resulted in excessive disk usage. Microsoft began working to give its search algorithm more signals to help it avoid peak usage time: understanding when power savings, gaming and other modes were turned on; when CPU usage and disk usage were high, etc.
Among the fixes introduced with 19025 include one that prevented Sandbox and Windows Defender Application Guard from workin in the previous flight (Build 19023, released earlier this week). A full list of the fixes in today's build are in the blog post about 19025.