My XenApp 5 farm published desktops running on Windows Server 2008 x86 had logon times averaging 69 seconds. Group Policy Registry items were taking 40 seconds as seen in the event logs.
I found Citrix article CTX128749. I added a new GPO with a scheduled task containing:
rd “C:ProgramDataMicrosoftGroup Policyhistory” /s /q
I ran the above command and restarted all servers and then timed logons and they had decreased from 69 to 33 seconds. I can live with 33 second logons.
Thanks and a shout out to robissimo for pointing the Citrix article out to me.