Well, other than not using that script there is not much which can be done about that as it is the script's fault.
You could always try to set up a faster ftp account or something, so the connection wil be faster. Or maybe you could contact the author of that script and explain the situation and asking him/her to make the uploading asyncronical (which therefor will not slow things down).
PS: since this has got nothing todo with Messenger Plus! itself, but with a script, I also have reported this thread to be moved to the scripting subforum. More chance there that the author of this script sees this...
/ 
