WebThumbnailExtension 100% cpu usage

I can produce this regularly by searching for kind:xls files and then having MacOS showing the Icon Preview.

The funny thing is that this appeared on both my computers at the same time, a Mac Studio, and a MacBookPro.

I believe there is a bug in the ICON PREVIEW generation for .xls files.

I have no Safari extensions and the issue arises when Safari is not running. Definitely a correlation with Spotlight search and Finder generating preview icons. Problems began shortly after updating to Sequoia.

for me this happens most of the time when I open a specific excel spreadsheet; so maybe there is the issue

This is causing a huge problem for me! My brandnew Maxbook Pro with an Apple M3 Max now just completely blocks for several minutes, several times a day. That is completely unaccaptable. I see about 10-20 of the same processes with this path:

/System/Library/Frameworks/WebKit.framework/Versions/A/XPCServices/com.apple.WebKit.WebContent.xpc/Contents/MacOS/com.apple.WebKit.WebContent

Parent Process: launchd (1)

Apple please fix ASAP! Thanks!

The issue for me was that some files synced by office ( probably outlook ) were causing this to happen whenever spotlight tried to index them. Maybe its the icon generation of .xls files like someone mentioned in this thread, but I can't 100% confirm that either.

The way I fixed it was to exclude all Microsoft Office folders from spotlight indexing. The ones starting with "UBF8" inside of "/Users/username/Library/Group Containers/".

I have the same issue what I tried to replicate the issue is I have bunch of '.xlsx' files in compressed in a '.rar' file once I extract those to any location it triggers the "WebThumbnailExtension Web Content" processes. I think it was mentioned before issue with Sequoia and Icon preview cause it only happens with those excel files with me.

Another thing I found online regarding trackpad and quick look function is not convincing and didn't do anything in my case also a user here has it with a Mac Studio.

I can confirm it is definetely Finder related.

Sorry it wasn;t this after all. Still do not know what.

FYI I had planmaker free open with safari doing copy and paste of web content into a spreadsheet.

it seems to be caused by Adblock and the other privacy extensions in safari.

I removed all of them and it's fine now (even duckduck for safari )I had a few of them running at the same time

Whoever wants to test them one by one is welcome to share the result

After having IT run forensic tests, including removing recently-added AV, and not being able to fix the problem I resorted to a factory reset of my device, and installed Sonoma instead of Sequoia. Everything is now running perfectly, including the previously-suspected AV software. So Sequoia is definitely the problem.

Anybody got a fix? This issue remains unsolved and happen when I open specific MS office excel files. I cannot find any solution - last OS X updates did not help; I still believe it's office related and my only hope there might be a fix with the next office update.

The problem disappeared on my two computers, but I don't know why.

Among others, I ran "brew update; brew upgrade" on both, and I also deleted Microsoft Office and reinstalled it from the Microsoft Office website via download. I also cleaned my computers with ONYX.

Can confirm this issue; having these issues since Sequoia update.

Seems to be related to Spotlight search.

remove all the privacy and adblock extensions from safari and uninstall the app them from your mac

should work

sounds plausible and would match my experience as described before