Bug: Search function (especially drive) causes high CPU/RAM leak, background hang, and prevents relaunch

[PS938-new]

Description

On Files Preview, resource usage is completely normal on startup (0.2%–0.6% CPU, ~86 MB RAM) during regular folder browsing. Compared to the previous stable version, the UI feels noticeably less laggy and has reduced jitteriness.

However, running a normal search function (especially across an entire drive like C:\) triggers an unconstrained background resource leak:

• CPU immediately jumps to ~58%–65% and RAM climbs past 500 MB.
• Navigating away to other folders does not cancel the search; high CPU and memory usage remain permanently stuck.
• Closing the window leaves a zombie background process running in Task Manager, which prevents the app from reopening until the task is manually killed.
• The image proof for resource usage of File Preview attached below 👇

Steps To Reproduce

1. Launch Files Preview and confirm baseline idle usage (~0.5% CPU).
2. Open a drive root (e.g., C:\) and use the normal search function to search for any file name.
3. Observe CPU and RAM consumption climb rapidly in Task Manager.
4. Navigate away from the search results into another folder (usage stays stuck at high levels).
5. Close the window and attempt to reopen Files Preview (the app fails to launch until the stuck background process is manually ended in Task Manager).

Files Version

4.2.37.0

Windows Version

10.0.26340.9502

User ID

6ad884bf-e124-4438-9f21-9fd4ef4d139d

Log File

debug.log

[Josh65-2201]

Thanks for the report, this is normal as Files has to use CPU to search. You can index the drive in Windows settings > Privacy & security > Search to make it faster, but there isn't anything we can do to make Windows search better.

We're tracking using a better search system in the below linked issue. You can check there or click subscribe in the right sidebar for updates.

[yair100]

@PS938-new there is a known issue with search using higher than expected CPU. We're tracking this in #4180 (search is specifically called out in the list of performance related issues).

[Josh65-2201]

For the background hang, where are you running the search on?

[PS938-new]

For the background hang, where are you running the search on?

I was running the search directly from the root of the system drive (C:\).

[Josh65-2201]

Closing the window leaves a zombie background process running in Task Manager, which prevents the app from reopening until the task is manually killed.

@workbysaran Wasn't #18646 suppose to fix the above issue?

Or is the limit from #18646 (comment)

[workbysaran]

@Josh65-2201

#18646 cancels the search when you navigate away or close a tab. The limitation is that Windows Search runs in-process as a COM server, so native search work that has already started can't be cancelled and keeps running until it finishes, especially on a large drive like C:. We may need an alternative, such as running search out of process.