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Windows Troubleshooting: Slow Operating System Boot Times and Slow User Logons (SBSL)

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This article describes Microsoft Support experiences in troubleshooting boot and logon delays.  The goal of this content is to create awareness among IT administrators, support professionals, and consultants, about the tools, cause, and resolutions for boot and user logon delays.   

Credits

Written by: A. Conner, David Everett, and Joey Seifert

Edited by: Justin Hall

Overview

A team in Commercial Technical Support dubbed the “SBSL” team for slow boot slow logon,” recently studied boot and user logon delays on domain-joined Windows clients and servers.

The team reviewed several hundred cases to identify:

  • The duration of delays encountered during the boot and logon process
  • On-screen messages displayed when boot and logon delays occurred
  • Common root causes for slow boots and logons

What the team found was:

  • A number of user logon delays were actually caused by delays in the OS startup process.
  • Common causes for both slow boots and user logons included:
    • Code defects in Windows clients, servers and domain controllers.
    • Code defects in Microsoft and ISV applications and utilities.
    • Admin configuration errors on client computers, server computers, and the underlying network.

In many of the cases, there were multiple code defects or misconfigurations contributing to boot and logon delays. This made the troubleshooting process iterative, where resolving the most obvious delay exposed subsequent delays.

  • Some delays were caused by significant workloads triggered by policy, scripts, and applications executing during the boot and logon process.
  • Administrators and support professionals struggled to create a crisp problem statement identifying
    • Which operation (OS boot or user logon) was slow?
    • How long was the boot and user logon operation was taking?
    • What phase of the boot or logon process was running long?
    • What UI was displayed on-screen when boot and logon hang occurred?
    • Goals for boot and logon times?
    • Hotfixes that resolved known slow boots in logons in Windows were frequently not installed on production clients and servers.
    • The lack of a detailed problem statement contributed to a troubleshooting process that was frequently not as efficient or structured as we had hoped.

Costs of boot and logon delays

To understand the impact of boot and logon delays, consider the following example:

  • Employees work 250 days per year (50 weeks * 5 days per week)
  • Employee labor costs $2 per minute
  • Each employees boots and logons to a single desktop computer once per day
  • There are 25 and 30 seconds of removable delay from the boot and logon operations

The 1-year cost for those two delays grows significantly with organization size, as illustrated in the following table. Opportunity costs could be even higher if delays exist in other operations like a desktop lock and unlock, user logoff or OS shutdown, or if users log onto multiple computers over the course of a workday.

Org Size Delayed Boot cost Delayed logon cost Total Cost
1 $208 $250 $458
5 $1,041 $1,250 $2,291
10 $2,083 $2,500 $4,583
20 $4,166 $5,000 $9,166
50 $10,416 $12,500 $22,916
100 $20,833 $25,000 $45,833
1,000 $208,333 $250,000 $458,333
10,000 $2,083,333 $2,500,000 $4,583,333
100,000 $20,833,333 $25,000,000 $45,833,333

Defining the problem

To get administrators and support professionals on the same page, a common criteria was needed to describe the delays taking place.

When troubleshooting a slow boot or logon problem, we recommend you use a clock or stopwatch (such as a stopwatch application on your phone) to record the number of seconds for different phases of the boot and logon process to complete.

There are four scenarios of interest to time:

  1. OS startup time
  2. User logon time following OS startup (before background OS startup processes have completed)
  3. 1st-time logons
  4. 2nd-time logons with cached credentials

If slow boot:

  1. Follow KB 325376 to enable verbose startup, shutdown, logon, and logoff status
  2. Turn on the Windows computer experiencing boot delays
  3. Note each unique message displayed during the boot process like “applying computer settings….” and the # of seconds that message was displayed until the appearance of the Secure Attention Sequence (CTRL+ALT+DEL) dialog.

Message strings displayed during OS boot

 # of seconds delays
<Message String 1>  
<Message String 2>  
<Message String 3>  
<Message String 4>  
<Message String 5>  
<Message String 6>  

Slow Logon – 1st-time logon

Slow user logons are frequently impacted by the background loading of OS components within a number of seconds, and in extreme cases hours, after OS startup. Compare 1st logon times immediately after OS restart against 1st-time logons for an identically configured user account when background OS startup has completed on the console or RDP server we are logging onto.

1st-time logons are delayed by the execution of Active Setup and the need to build user profiles derived from default user profiles.

  1. Follow KB 325376 to enable verbose startup, shutdown, logon, and logoff status
  2. Log onto the computer Windows computer experiencing logon delays
  3. Note each unique message displayed during the logon process like “applying user settings….” after entering valid credentials until the Windows desktop loads and becomes responsive to mouse and keyboard input.
  4. Repeat step 2 after the background loading of OS components has completed
Message String Logon # of seconds following OS startup

Logon # of seconds after background OS startup complete

 Logon # of seconds with cached credentials
       
       
       
       
       

Slow Logon – 2nd-time logon

Subsequent or “2nd time” logons are normally faster than first-time logons due to the use of a locally cached user profile, unless policy has been configured to delete such profiles after user logoff, or N # of days after the profile was created, or mandatory profiles have been assigned, in which case every logon is like a first-time logon, deriving a new profile from a default profile.

  1. Follow KB 325376 to enable verbose startup, shutdown, logon, and logoff status.
  2. Log onto the computer Windows computer experiencing logon delays.
  3. Note each unique message displayed during the logon process like “applying user settings….” after entering valid credentials until the Windows desktop loads and becomes responsive to mouse and keyboard input.
  4. Repeat step 2 after the background loading of OS components has completed.
Message String Logon # of seconds following OS startup Logon # of seconds after background OS startup complete Logon # of seconds with cached credentials