Why does first HTTPS, FTPS or SMTPS connection to the server take more time than subsequent connections?
There can be several reasons for this.
First of all, if you use TElX509CertificateValidator component to validate server certificates, this component performs complete certificate chain validation during first connection. On subsequent connections it already has some data (CRLs, cached certificates) and validation is performed almost instantly.
Next, in .NET edition, when the operation is initiated, .NET framework loads backend assemblies (SecureBlackbox.dll, SecureBlackbox.SSLCommon.dll, SecureBlackbox.SSLClient.dll) and this takes some time. Subsequent calls are almost instant too.
Finally, it can be a firewall trouble - the firewall scans the rule table each time the application takes some action for the first time. Next the rules are remembered and so processing is faster.