WebThumbnailExtension Web Content High CPU/Memory Usage

Just wanted to post that the solution here worked for me -

Looks like Quick Look is the culprit, and I never use it, so this was a pretty painless bandaid until they patch it.

Open System Preferences > Trackpad > Point & Click, and uncheck "Look up & data detectors."

[Edited by Moderator]

Finally, I was able to solve the issue! You may kill running process, but this not solve the cause. Only allows you work for a few more minutes. It was frustratring.

I tried reinstalling/repair OS and did not helped either.

I got all cores under fire by opening Finder or using spotlights randomly. 100% utilization was caused by broken index and spotlight tried to index folder with large files, xml (and AI models in my case)

Only I had to do, was adding the folder to blacklist - prevent indexing.

Sequoia (15.3.1): System Settings -> Spotlight -> Search Privacy (at the bottom).

Add folder you want to exclude and wait for a while.

I started with home folder and gradually was able to isolate one project, that caused the issue. The rest of home folder has been reindexed and spotlight is working as has never before.

I had my default browser set to Zen Browser (which is firefox based). In this case opening images in preview for example starts these pesky hogging thumbnail extension processes. As you state @bravebro, setting my default browser to safari fixes this specific problem. But still I want to not have to set my default browser to safari when I want to use something else.

I have a new Macbook Pro M4 and noticed this problem.

In Activity Monitor I clicked the info button and then open ports and files.

I could see one huge Excel file as the problem. It's an archive I'd like to keep but never use.

I zipped the Excel file and trashed the original. Problem solved.

I don't have any MS Office apps installed.

After I had the issue with my M1 MacBook Air over several OS versions, I encountered it again on a new MacBook Air M4 (with MacOS 15.3.2). Pretty disappointing that this does not seem to have been fixed up for years now.

After trying the various approaches discussed here and elsewhere (QuickLook, Browsers etc.), several times and with reboots, I closed office (Excel and Word) and eventually threw them from my disk. This solved the issue immediately. No WebThumbnailExtension Web Content since then...

hi all.

I solved the problem by turning off the spotlight search index.

I just unchecked the "folders" line.

I suffered from this issue for more than a month. Now everything is ok.

I've been running into this issue. Initially, I thought it was because my MBP M3 Max was connected to the Microsoft Redmond domain and that Intune MDM policies were buggy. I'm not sure QuickLook is the culprit (rather, I'm looking at you Excel and PowerPoint, or Teams 😏). Anyway, for awhile, whenever my CPU starts hitting 100% and computer starts becoming sluggish, I was using Activity Monitor to force quit all those pesky WebThumbnailExtension Web Content instances.

You can also use Automator to make an "app" that will programmatically kill those instances on demand. Here's the Run Shell Script I use:

#!/bin/bash

# Search for the processes and extract their PIDs
PIDS=$(ps -axo pid,command | grep -i "System/Library/Frameworks/WebKit.framework/Versions/A/XPCServices/com.apple.WebKit.WebContent.xpc/Contents/MacOS/com.apple.WebKit.WebContent" | grep -v grep | awk '{print $1}')

# Check if any PIDs were found
if [ -n "$PIDS" ]; then
    echo "Killing the following processes:"
    echo "$PIDS"
    echo "$PIDS" | xargs kill -9
    echo "Processes terminated."
else
    echo "No matching processes found."
fi

Hope this helps!

When I changed my default browser to Google Chrome, I had the same problem.

After changing the default browser to Safari again, problem get solved.

At the moment, the only solution I found is to close Safari, "Force Quit" every instances of "WebThumbnailExtension Web Content" in Activity Monitor, then use other browsers (e.g. Chrome, Firefox, etc.).

Interesting. I escalated the issue to Apple Support and eventually spoke with a senior Apple tech who advised that the issue likely to be a bug when upgrading from OSX 14 to OSX 15. They suggested I do a completely clean reinstall which they are yet to guide me through. I am sceptical though, given the extensive comments posted here from people who already done this :-)

I also notice that the memory pressure issues seem to relate to use of Preview and Office when concurrently running. FWIW I did provide a link to this discussion group to the Apple tech, and suggested they look imto this in more detail.

找到一个临时解决方案，暂时解决了这个问题：https://junki.cn/archives/Ag0GinQV

FWIW since the OSX 15.4 update I have not had the problem any more. Fingers crossed!

Problem still exists with Sequoia 15.3.1 update. I am running a 2019 iMac without track pad, so that's not the issue. Memory issues 'appear' to escalate when I am using Preview. If I go into Activity Monitor and click on the offending multiple WebThumbnailExtension Web Content processes and click 'quit' they remain open; I have to force quit them and then all is well.

Can Apple PLEASE address this issue as it's quite annoying to have processes freeze & crash due to lack of memory whenw in fact my iMac has oddles of memory in reserve.

I have exactly the same issue you have with Preview appearing to be the triggering culprit. HOWEVER I am using Safari as my usual browser, so in my case using Safari doesn't solve the issue. I see that there is a Sequoia 15.3.2 update just released today, but looking at the description it doesn't look like this issue is being addressed...

Further to the above, I have run an EtreCheck scan which highlights these issues. Hopefully someone at Apple will read this :-)

Diagnostics Information (past 60 days):

    2025-03-12 11:41:35 apfsd - High CPU Use (2 times)

        First occurrence: 2025-03-12 09:55:49

        Executable: /usr/libexec/apfsd

    2025-03-12 11:41:05 spotlightknowledged - High CPU Use

        Executable: /System/Library/Frameworks/CoreSpotlight.framework/spotlightknowledged

    2025-03-12 09:50:39 lsd - Crash (6 times)

        First occurrence: 2025-03-12 09:50:34

        Executable: /usr/libexec/lsd

    2025-03-11 16:22:05 com.apple.WebKit.WebContent - High CPU Use

        Details: 

            "com.apple.Safari"(1079)

    2025-03-11 15:55:57 com.devguru.DriverKit.SamsungMTP - High CPU Use