Product:
Cognos TM1 10.2
Windows 2008 R2 Server

Symptom:
TM1 application web is slow and it is resolved by restarting the TM1 Application service (tomcat).

Possible Solution:
1) In IBM Cognos Configuration of TM1, select Environment >TM1 Application Server, and increase “Maximum Memory in MB” from 768 to 1024 or 1536. The maximum that it can be set from this GUI is 4096 (in version 10.1x) – if set that high, be sure that the server has enough memory available to accommodate it. Restart the TM1 Application Server.

NOTE: In versions 10.2x the memory can be set higher than 4096 through the Cognos Configuration GUI – but, again, make sure there is enough RAM on the machine to accommodate it.

2) Launch the Apache Tomcat manager GUI from the cmd line (run the command prompt by using Run as Administrator) and navigate to the install directory for TM1 and the Tomcat bin folder (eg: C:\Program Files\ibm\cognos\tm1_64\tomcat\bin).
Type this:
tomcat6w.exe //ES//pmpsvc
Navigate to the Java tab, and in the Java Options window, navigate to the bottom of the options list and add in the following:
-Xgcpolicy:gencon
(the default garbage collector policy is “optthruput”)
Validate and close the window and restart TM1 Application Server.

Below is the list of default values for the TM1 Tomcat java:
-Dcatalina.base=C:\Program Files\ibm\cognos\tm1_64\tomcat
-Dcatalina.home=C:\Program Files\ibm\cognos\tm1_64\tomcat
-Djava.endorsed.dirs=C:\Program Files\ibm\cognos\tm1_64\tomcat\common\endorsed
-Djava.io.tmpdir=C:\Program Files\ibm\cognos\tm1_64\tomcat\temp
-Dorg.apache.tomcat.util.buf.UDecoder.ALLOW_ENCODED_SLASH=true
-Xmx768m
-XX:MaxNewSize=384m
-XX:NewSize=192m
-XX:MaxPermSize=128m
-Dcom.sun.management.jmxremote.port=7999
-Dcom.sun.management.jmxremote.authenticate=false
-Dcom.sun.management.jmxremote.ssl=true
-Dcom.sun.management.jmxremote.password=false
-Djmx.remote.x.server.connection.timeout=1000

NOTE: If you set the properties using the Apache Tomcat administration tab, start the TM1 Application Server using the Component Services option–do not use Cognos Configuration in that case as Cognos Configuration then resets the properties back to the shipped defaults.

3) If the server is a Virtual Machine (VMWare, ESXi) then go to Windows Control Panel, System and Security, Power Options, and change the power plan from “Balanced” to “High performance”.

4) Add exclusions to the antivirus to prevent “C:\Program Files\ibm\cognos\tm1_64\tomcat” and “C:\Program Files\ibm\cognos\tm1_64\webapps” from being scanned. Skipping scanning of all TM1 files is preferred – see below link.

5) Verify DEP is set to “Essential Windows programs and services only”. To do this : Right-click the”Computer” icon on your desktop, select “Properties”, select “Advanced System Settings”, select “Advanced” tab, under “Performances”, “Settings” button, “Data Execution Prevention” tab.

More Information
http://www-01.ibm.com/support/docview.wss?uid=swg21669247
http://www-01.ibm.com/support/docview.wss?uid=swg21454290