What is the scheduled task "\Microsoft\Windows\Windows Defender\Windows Defender Cache Maintenance" on my Windows 8 computer?

"\Microsoft\Windows\Windows Defender\Windows Defender Cache Maintenance" is a scheduled task on Windows 8 system added as part of Windows installation.

You will see "\Microsoft\Windows\Windows Defender\Windows Defender Cache Maintenance" listed on Task Scheduler with the following information:

Name: Windows Defender Cache Maintenance
Location: \Microsoft\Windows\Windows Defender
Description: Periodic maintenance task.
Actions: C:\Program Files\Windows Defender\MpCmdRun.exe -IdleTask 
   -TaskName WdCacheMaintenance
Triggers: 
History: 
   Information 8:24:00 Task completed
   Information 8:00:48 Action completed
   Information 8:00:48 Action started
   Information 8:00:48 Task started
   Information 8:00:48 Created task process
   ...

Programe file information about "MpCmdRun.exe":

File name: MpCmdRun.exe
File path: C:\Program Files\Windows Defender\MpCmdRun.exe
File size: 352208 bytes
Last modified time: 7/1/2013 8:44:21 PM
File description: Microsoft Malware Protection Command Line Utility
File version: 4.3.0215.0
Company name: Microsoft Corporation

"MpCmdRun.exe" is scheduled to run with no triggers.

It is recommended to keep "\Microsoft\Windows\Windows Defender\Windows Defender Cache Maintenance" enabled as a scheduled task.

⇒System Scheduled Tasks on Windows 8

⇒⇒Windows 8 Scheduled Tasks