You said you have modified the script... mIRC is not the best way to use scripts on servers (although its the only way currently in VC:MP). I have noticed that the script sometimes gets quite slow responding, if the size of the script gets big (>100kB) or theres lots of complex aliases the same command uses. Also on LW the echo is sometime slow, dunno whats the reason is there (perhaps same?). Skype and others doesnt affect much, unless you're hosting some conference call at the same time, but in stand by mode the traffic caused by skype is very slow.