It's quite instantaneous here. Can you describe your system? mIRC version, scripts, etc?
The following will help answer some of the above questions:
//echo -a $md5($mircexe,2) $version $os $script(0) $dll(0)
Lastly, are all the windows maximized when you do this? If not, can you describe how your windows are setup? If the window needs to be maximized, you can expect a delay, there's not much mIRC can do about this.
