What is the use of WPFFontCache Service in WPF? WPFFontCache_v0400.exe taking 100 % CPU all the time this exe is running, why?

Question

What is acutally the functionality of WPFFontCache in WPF?. Sometime it is takeing too much CPU usage because of this system in hanging and my Application. Is there any problem disabling the service from the windows service. The big concern is why it is hanging my Application?.

Answer 1

From MSDN:

The WPF Font Cache service shares font data between WPF applications. The first WPF application you run starts this service if the service is not already running. If you are using Windows Vista, you can set the "Windows Presentation Foundation (WPF) Font Cache 3.0.0.0" service from "Manual" (the default) to "Automatic (Delayed Start)" to reduce the initial start-up time of WPF applications.

There's no harm in disabling it, but WPF apps tend to start faster and load fonts faster with it running.
It is supposed to be a performance optimization. The fact that it is not in your case makes me suspect that perhaps your font cache is corrupted. To clear it, follow these steps:

1. Stop the WPF Font Cache 4.0 service.
2. Delete all of the WPFFontCache_v0400* files. In Windows XP, you'll find them in your C:\Documents and Settings\LocalService\Local Settings\Application Data\ folder.
3. Start the service again.