Barring a last minute delay, Microsoft will begin pushing out its May 2020 update for Windows 10 in a matter of weeks. It's the first of two major upgrades to Windows 10 scheduled for this year, and with it will come a minor change to how Windows search indexes files, which could have a big impact on performance on some older PCs.
How big of an impact will depend on your particular setup. PCs running a hard drive as the primary storage stand to benefit the most, especially ones that only spin at 5400 RPM, instead of 7200 RPM. These are still fairly common on older or cheap laptops.
What's changing is when Windows search indexes files. The May 2020 update will bring about tweaks to the algorithm Windows 10 uses to detect high disk usage. Importantly, it will better identify peak usage times so it can avoid thrashing your HDD (or SSD) in certain situations.
This is something Microsoft outlined in November 2019 and has been testing in its Windows Insider program ever since. In addition to better identifying peak usage times, the update makes "changes for developers to prevent searches of certain repositories and project folders to improve disk usage."
Will it really matter? It does according to Windows Latest, which tested a preview build and said it "actually feels faster if your hardware is equipped with an HDD."
You're less likely to notice a difference if your main drive is an SSD, though the improved algorithm applies to both types of storage. And if you've ever noticed unusually high CPU usage because of Window's indexing scheme, you could potentially still see a bump in performance even with an SSD, just temper your expectations.
Somewhat related, the May 2020 update will alter the Performance tab in the Task Manager to show the drive type—SSD or HDD instead of just Disk 1 and Disk 2—and will also add a GPU temp monitor.