Hi cpac,
First I would like to say that the example was just made for the perfect situation with the file open in TextEdit and the text exactly as you stated. You propbably know this but there should be error checking added.
(1)
You are correct about the execution of the script. Although, the length of the script doesn’t determine its speed. I did several quick tests which shows the speed difference. It uses Jon’s Commands scripting addition’s command ‘the ticks’:
http://www.seanet.com/~jonpugh/
Here’s the first with the if…then conditional:
property tag_list : {{“myFName”, “Ciaran”}, {“myMName”, “P. A.”}, {“myLName”, “Connelly”}}
tell application “TextEdit”
activate
set t1 to (the ticks)
repeat with this_tag in tag_list
set the_tag to item 1 of this_tag
set rstring to item 2 of this_tag
set word_count to (count words of rstring)
tell text of front document
if word_count is 1 then
set (every word whose it is the_tag) to rstring
else
set tag_count to count (every word whose it is the_tag)
repeat with i from tag_count to 1 by -1
set (word i of every word whose it is the_tag) to rstring
end repeat
end if
end tell
end repeat
set t2 to (the ticks)
end tell
set d to t2 - t1
activate
display dialog d
– 16, 10, 13, 14, 14 ticks
Here’s the second script using a repeat loop for every tag:
property tag_list : {{“myFName”, “Ciaran”}, {“myMName”, “P. A.”}, {“myLName”, “Connelly”}}
tell application “TextEdit”
activate
set t1 to (the ticks)
repeat with this_tag in tag_list
set the_tag to item 1 of this_tag
set rstring to item 2 of this_tag
tell text of front document
set tag_count to count (every word whose it is the_tag)
repeat with i from tag_count to 1 by -1
set (word i of every word whose it is the_tag) to rstring
end repeat
end tell
end repeat
set t2 to (the ticks)
end tell
set d to t2 - t1
activate
display dialog d
– 26, 25, 27, 27, 28 ticks
As you can see, it took about twice as long for the second script. There are probably other ways to decrease the speed, but it would be a long story.
About the “special” characters, there are other characters that separate words and some that are words in itself. I placed a list of these characters in a post once, but can’t remember what they were right now. I think one was the “-” sign etc.
(2)
The AppleScriptLanguageGuide says that the ‘every element’ reference form returns a list. This is partially true, but it’s not a list when you use it in the same statement. What I meant was that if you use a command mixed with this reference form, then it works on each element, but not the list as a whole in the sense of lists. What? Anyway, hard to explain. I call this list a multi threaded list (made this up). 
I was trying to think of a good example of this and am working on it, but here’s a quicky using the Finder:
(a) command + every element
set desk_path to (path to desktop) as string
tell application “Finder”
activate
try
make new folder at desktop with properties {name:“My Folder”}
set folder_ref to result
on error
set folder_ref to folder (desk_path & “My Folder” & “:”)
end try
open folder_ref
repeat with i from 1 to 3
set file_name to (“File” & i)
make new file at folder_ref with properties {name:file_name}
end repeat
delay 1
set name_list to (name of every file of folder_ref)
end tell
(b) command + real list
set desk_path to (path to desktop) as string
tell application “Finder”
activate
try
make new folder at desktop with properties {name:“My Folder”}
set folder_ref to result
on error
set folder_ref to folder (desk_path & “My Folder” & “:”)
end try
open folder_ref
repeat with i from 1 to 3
set file_name to (“File” & i)
make new file at folder_ref with properties {name:file_name}
end repeat
delay 1
set file_list to every file of folder_ref
set name_list to (name of file_list)
end tell
This second example errors because you can’t get the name of a list. However, the previous script works because you’re getting the name of each file seperately and does not work on the list as a whole. Can you see how it works When used in the same statement? How do you like my “multi-threaded list” name for this type of list?
gl,