Performance analyzer for Microsoft Defender Antivirus

What is Microsoft Defender Antivirus performance analyzer?

In some cases, you might need to tune the performance of Microsoft Defender Antivirus as it scans specific files and folders. Performance analyzer is a PowerShell command-line tool that helps determine which files, file extensions, and processes might be causing performance issues on individual endpoints. This information can be used to better assess performance issues and apply remediation actions.

Some options to analyze include:

  • Top files that impact scan time
  • Top processes that impact scan time
  • Top file extensions that impact scan time
  • Combinations – for example, top files per extension, top scans per file, top scans per file per process

Running performance analyzer

The high-level process for running performance analyzer involves the following steps:

  1. Run performance analyzer to collect a performance recording of Microsoft Defender Antivirus events on the endpoint.

    Note

    Performance of Microsoft Defender Antivirus events of the type Microsoft-Antimalware-Engine are recorded through the performance analyzer.

  2. Analyze the scan results using different recording reports.

Using performance analyzer

To start recording system events, open PowerShell in administrative mode and perform the following steps:

  1. Run the following command to start the recording:

    New-MpPerformanceRecording -RecordTo <recording.etl>

    where -RecordTo parameter specifies full path location in which the trace file is saved. For more cmdlet information, see Defender.

  2. If there are processes or services thought to be affecting performance, reproduce the situation by carrying out the relevant tasks.

  3. Press ENTER to stop and save recording, or Ctrl+C to cancel recording.

  4. Analyze the results using the performance analyzer’s Get-MpPerformanceReportparameter. For example, on executing the command Get-MpPerformanceReport -Path <recording.etl> -TopFiles 3 -TopScansPerFile 10, the user is provided with a list of top-ten scans for the top 3 files affecting performance.

For more information on command-line parameters and options, see the New-MpPerformanceRecording and Get-MpPerformanceReport.

Note

When running a recording, if you get the error "Cannot start performance recording because Windows Performance Recorder is already recording", run the following command to stop the existing trace with the new command: wpr -cancel -instancename MSFT_MpPerformanceRecording

Performance tuning data and information

Based on the query, the user will be able to view data for scan counts, duration (total/min/average/max/median), path, process, and reason for scan. The image below shows sample output for a simple query of the top 10 files for scan impact.

Example output for a basic TopFiles query

Additional functionality: exporting and converting to CSV and JSON

The results of the performance analyzer can also be exported and converted to a CSV or JSON file. For examples that describe the process of "export" and "convert" through sample codes, see below.

For CSV

  • To export: (Get-MpPerformanceReport -Path:.\Repro-Install.etl -Topscans:1000). TopScans | Export-CSV -Path:.\Repro-Install-Scans.csv -Encoding:UTF8 -NoTypeInformation

  • To convert: (Get-MpPerformanceReport -Path:.\Repro-Install.etl -Topscans:100). TopScans | ConvertTo-Csv -NoTypeInformation

For JSON

  • To convert: (Get-MpPerformanceReport -Path:.\Repro-Install.etl -Topscans:1000). TopScans | ConvertTo-Json -Depth:1

Requirements

Microsoft Defender Antivirus performance analyzer has the following prerequisites:

  • Supported Windows versions: Windows 10, Windows 11, and Windows Server 2016 and above
  • Platform Version: 4.18.2108.7+
  • PowerShell Version: PowerShell Version 5.1

PowerShell reference

There are two new PowerShell cmdlets used to tune performance of Microsoft Defender Antivirus:

New-MpPerformanceRecording

The following section describes the reference for the new PowerShell cmdlet New-MpPerformanceRecording. This cmdlet Collects a performance recording of Microsoft Defender Antivirus scans.

Syntax: New-MpPerformanceRecording

New-MpPerformanceRecording -RecordTo <String >

Description: New-MpPerformanceRecording

The New-MpPerformanceRecording cmdlet collects a performance recording of Microsoft Defender Antivirus scans. These performance recordings contain Microsoft-Antimalware-Engine and NT kernel process events and can be analyzed after collection using the Get-MpPerformanceReport cmdlet.

This New-MpPerformanceRecording cmdlet provides an insight into problematic files that could cause a degradation in the performance of Microsoft Defender Antivirus. This tool is provided “AS IS”, and is not intended to provide suggestions on exclusions. Exclusions can reduce the level of protection on your endpoints. Exclusions, if any, should be defined with caution.

For more information on the performance analyzer, see Performance Analyzer docs.

Important

This cmdlet requires elevated administrator privileges.

Supported OS versions

Windows Version 10 and later.

Note

This feature is available starting with platform version 4.18.2108.X and later.

Examples: New-MpPerformanceRecording

Example 1: Collect a performance recording and save it
New-MpPerformanceRecording -RecordTo:.\Defender-scans.etl

The above command collects a performance recording and saves it to the specified path: .\Defender-scans.etl.

Parameters: New-MpPerformanceRecording

-RecordTo

Specifies the location in which to save the Microsoft Defender Antimalware performance recording.

Type: String
Position: Named
Default value: None
Accept pipeline input: False 
Accept wildcard characters: False

Get-MpPerformanceReport

The following section describes the Get-MpPerformanceReport PowerShell cmdlet. Analyzes and reports on Microsoft Defender Antivirus (MDAV) performance recording.

Syntax: Get-MpPerformanceReport

Get-MpPerformanceReport    [-Path] <String>
[-TopScans <Int32>]
[-TopFiles  <Int32>
	[-TopScansPerFile <Int32>]
	[-TopProcessesPerFile  <Int32>  
		[-TopScansPerProcessPerFile <Int32>]
	]
] 
[-TopExtensions  <Int32>
	[-TopScansPerExtension <Int32>]
	[-TopProcessesPerExtension <Int32>
		[-TopScansPerProcessPerExtension <Int32>]
		]
	[-TopFilesPerExtension  <Int32>
		[-TopScansPerFilePerExtension <Int32>]
		]
	] 
]
[-TopProcesses  <Int32>
	[-TopScansPerProcess <Int32>]
	[-TopExtensionsPerProcess <Int32>
		[-TopScansPerExtensionPerProcess <Int32>]
	]
]
[-TopFilesPerProcess  <Int32>
	[-TopScansPerFilePerProcess <Int32>]
]
[-MinDuration <String>]

Description: Get-MpPerformanceReport

The Get-MpPerformanceReport cmdlet analyzes a previously collected Microsoft Defender Antivirus performance recording (New-MpPerformanceRecording) and reports the file paths, file extensions, and processes that cause the highest impact to Microsoft Defender Antivirus scans.

The performance analyzer provides an insight into problematic files that could cause a degradation in the performance of Microsoft Defender Antivirus. This tool is provided "AS IS" and is not intended to provide suggestions on exclusions. Exclusions can reduce the level of protection on your endpoints. Exclusions, if any, should be defined with caution.

For more information on the performance analyzer, see Performance Analyzer docs.

Supported OS versions

Windows Version 10 and later.

Note

This feature is available starting with platform version 4.18.2108.X and later.

Examples: Get-MpPerformanceReport

Example 1: Single query
Get-MpPerformanceReport -Path:.\Defender-scans.etl -TopScans:20
Example 2: Multiple queries
Get-MpPerformanceReport -Path:.\Defender-scans.etl -TopFiles:10 -TopExtensions:10 -TopProcesses:10 -TopScans:10
Example 3: Nested queries
Get-MpPerformanceReport -Path:.\Defender-scans.etl -TopProcesses:10 -TopExtensionsPerProcess:3 -TopScansPerExtensionPerProcess:3
Example 4: Using -MinDuration parameter
Get-MpPerformanceReport -Path:.\Defender-scans.etl -TopScans:100 -MinDuration:100ms

Parameters: Get-MpPerformanceReport

-MinDuration

Specifies the minimum duration of any scan or total scan durations of files, extensions, and processes included in the report; accepts values like 0.1234567sec, 0.1234ms, 0.1us, or a valid TimeSpan.

Type: String
Position: Named
Default value: None
Accept pipeline input: False 
Accept wildcard characters: False
-Path

Specifies the path(s) to one or more locations.

Type: String
Position: 0
Default value: None
Accept pipeline input: True
Accept wildcard characters: False

-TopExtensions

Specifies how many top extensions to output, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopExtensionsPerProcess

Specifies how many top extensions to output for each top process, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopFiles

Requests a top-files report and specifies how many top files to output, sorted by "Duration".

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopFilesPerExtension

Specifies how many top files to output for each top extension, sorted by "Duration".

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopFilesPerProcess

Specifies how many top files to output for each top process, sorted by "Duration".

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopProcesses

Requests a top-processes report and specifies how many of the top processes to output, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopProcessesPerExtension

Specifies how many top processes to output for each top extension, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopProcessesPerFile

Specifies how many top processes to output for each top file, sorted by "Duration “.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopScans

Requests a top-scans report and specifies how many top scans to output, sorted by "Duration".

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopScansPerExtension

Specifies how many top scans to output for each top extension, sorted by "Duration".

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopScansPerExtensionPerProcess

Specifies how many top scans to output for each top extension for each top process, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopScansPerFile

Specifies how many top scans to output for each top file, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopScansPerFilePerExtension

Specifies how many top scans to output for each top file for each top extension, sorted by "Duration".

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopScansPerFilePerProcess

Specifies how many top scans for output for each top file for each top process, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopScansPerProcess

Specifies how many top scans to output for each top process in the Top Processes report, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopScansPerProcessPerExtension

Specifies how many top scans for output for each top process for each top extension, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

-TopScansPerProcessPerFile

Specifies how many top scans for output for each top process for each top file, sorted by "Duration”.

Type: Int32
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False