Adobe Reader X slow to load in Remote Desktop Environment when multiple users have the application r

I have Adobe Reader X installed in a Remote Desktop (Citrix XenApp 6.5) environment and find the more people running the process the slower it is to load (it can take up to 15 seconds).  The delay is not related to how loaded the servers are and all other applications load very quickly.  I have tried disabling protected mode and messages, but it does not help.  Does anyone know what is going on here?  Thanks.