If you have access to help for SilkTest, search for Start Method. I think this is under thesExtensionReady or nInvokeTimeout descriptions.
It could be here (from sExtensionReady description):
"If bExtensionReady is not defined in the MainWin declaration and if the wStartup member of the MainWin declaration is defined and not null, Silk Test Classic interprets the wStartup value as a window and specifies its tag for sExtensionReady. Silk Test Classic looks for the specified window until the timeout expires."
Since bExtensionReady is NULL, the script is going on to the OPT_WINDOW_TIMEOUT and waiting 100 seconds until it executes the next line.
Of course, I could be wrong. If I am, sorry.