Performance issues or delays when you connect to Exchange Server 2013 that is running in Windows Server

Applies to: Windows Server 2012 R2 DatacenterWindows Server 2012 R2 StandardWindows Server 2012 R2 Essentials More


When you connect to a Microsoft Exchange Server 2013 server that is installed in Windows Server 2012 R2, Windows Server 2012, Windows Server 2008 R2, or Windows Server 2008 in which Microsoft .NET Framework 4.5 is included, you may experience delays to access email messages or disconnections to the Exchange server. When this issue occurs, the CPU or memory usage on the server is high for some services that include one or more of the W3wp.exe processes.


This issue occurs because too many objects are pinned on the .NET Framework 4.5 garbage collector heap. It causes heap fragmentation in addition to an increase in CPU and memory usage by the garbage collector.


To resolve this issue, use one of the following methods.

Method 1

Install the .NET Framework 4.5.2.

Note By using this method, you do not have to install hotfix 2803755 or add other registry keys.

Method 2

Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

By default, Exchange Server 2013 collects performance monitor data, and then stores the data in the following location:
C:\Program Files\Microsoft\Exchange Server\V15\Logging\Diagnostics\DailyPerformanceLogs
Performance monitor can be used to determine whether there are issues with .Net in garbage collector counter. To do this, follow these steps:
  1. Open a log that is in relation to the performance issue, and then add the .NET CLR Memory - % Time in GC counter.
  2. Then, add the following instances in the Instances of selected object field:
    • Microsoft.Exchange.RpcClientAccess.Service
    • W3wp and all remaining W3wp processes
The average of these counters should not exceed 10.