I have downloaded and started to install XenDesktop 7, the first thing that I noted that Citrix Studio was extremely slow to start.  I shrugged it off as first time launch but after subsequent reboots I notice the issue still persisted.  I have seen this issue lots in past and its mostly because of no internet access which is needed to check the signed dll with trusted CA. To workaround the issue we can disable this check as per below:

Open IE – Internet Options – Advanced tab – Untick the setting “Check for publisher’s certificate revocation”