The Case of the Mysterious Presentation Font Cache CPU Hog

Your PC worked perfectly fine the other day, but suddenly, it’s acting up. Performance went down, CPU activity increased, and your laptop’s or desktop’s fan is going wild—there’s clearly some resource hog affecting your system.

If our tuning tips didn’t resolve your situation, you might want to look at Windows Task Manager (hit CTRL+SHIFT+ESC at the same time). Over the past few months, I’ve heard that PresentationFontCache.exe is known to run amok and consume 50% of your processor’s resources. And, it actually seems to be a rather common problem. If this is happening on your system, we have the right fixes for you!

PresentationFontCache.exe is running constantly at 50% CPU usage—it's time to put a stop to this

What is Presentation Font Cache?

The Presentation Font Cache is part of the Windows Presentation Foundation (WPF) feature, which allows programmers to develop graphically richer applications. It’s part of the .NET Framework (3.0, 3.5, 3.5 SP1 and 4.0), which, in turn, is part of Windows Vista (3.0) and Windows 7 (3.5).

Some of your installed applications may require WPF and make use of the Presentation Font Cache. This service loads font glyph information into memory and helps share these fonts with all of the installed WPF applications. As such, applications that use the WPF framework start a bit quicker, and font pickers (such as this one) might see a slight performance increase.

By default, this service is set to manual, so it won’t launch automatically and cause performance improvements (in non-WPF applications) or any problems. However, once you use a WPF program, this service will start and—in some cases—set to start automatically when Windows launches!

Why is it burning my CPU?

The Presentation Font Cache loads all fonts into its font cache (which is stored on your hard disk, but more on that later). However, at some point, this cache may become corrupted and unreadable due to a specific font. Then, the Presentation Font Cache will start to become unresponsive and get caught in a “I try to launch, but I’m stuck, so I will try it again” loop. That’s what causes the incredibly high CPU usage, and what may even result in a sudden shutdown due to overheating. Luckily, there are a few solutions to this problem!

Solution #1: Delete the font cache file

The font cache is located under the following folder: %windir%\ServiceProfiles\LocalService\AppData\Local. Simply hold down the WIN key on your keyboard and press “R”. Then, enter the path above and click “OK”. Delete all the “FontCache…dat” files you find, such as “FontCache-System.dat” or “FontCache3.0.0.0.dat”.

This will cause the WPF font cache to rebuild itself. However, if the problem persists, you might need to shut down the WPF font cache permanently.

Solution #2: Shutting down the WPF font cache

If all else fails, you have no choice but to disable the font cache. This may cause a slight slowdown when loading applications that heavily rely on fonts or offer a font picker (which loads hundreds or even thousands of your installed fonts). But, it’s a lot less painful then working under 50% CPU stress and hearing a fan working on overdrive. So how do you get rid of WPF font cache? It’s simple—go to “Control Panel”, and click on “System and Security”, “Administrative Tools” and “Services”. Scroll all of the way down until you see “Windows Presentation Foundation Font Cache”. Double-click on this entry, and select “Disabled” from the “Startup type” list.

That’s it! Click on “OK”, and reboot your system. You may encounter some slight delays in your WPF applications, but at least your PC will be running at full speed again.

We hope that this blog post solved your problem—if not, leave us a comment below, and we’ll try to figure out the issue!