One of the ways to improve application startup time is to prevent application connecting to the network several times to download current certificate revocation list and verifying the signed assemblies. To prevent use: “<generatePublisherEvidence enabled="false"/>” in your application config file.
Authenticode verification adds to the startup time. Authenticode-signed assemblies have to be verified with the certification authority (CA). This verification can be time consuming, because it can require connecting to the network several times to download current certificate revocation lists. It also makes sure that there is a full chain of valid certificates on the path to a trusted root. This can translate to several seconds of delay while the assembly is being loaded.
Consider installing the CA certificate on the client computer, or avoid using Authenticode when it is possible. If you know that your application does not need the publisher evidence, you do not have to pay the cost of signature verification.
Starting in .NET Framework 3.5, there is a configuration option that allows the Authenticode verification to be bypassed. To do this, add the following setting to the app.exe.config file:
http://msdn.microsoft.com/en-us/library/bb629393.aspx //GeneratePublisherEvidence element.