WebThumbnailExtension 100% cpu usage

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/".

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

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.

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.

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

should work

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 must admit that I had installed all kinds of things using homebrew.

I am not sure, but my feeling is that things got a bit better since the last "brew update; brew upgrade".

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.

I can confirm it is definetely Finder related.

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

It seems to happen only when some excel type of files is open (whatever the program)

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!

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.

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.