My Bold Script is slow

[Björnke von Gierke]

Well, my bold Script is really slow, and I would appreciate any input 
for making it faster. Concrete are the loops at the bottom the problem, 
but I don't know an other way to change the bold, but leave other styles 
alone, as the forever-be-damned-and-burn-in-hell "textstyle" property is 
set to the uglier-as-my-dogs-ass "mixed" state.

here it comes, please be aware, that any brain injures caused by this 
script are the brain owners problem:

on mouseUp
     repeat with myChar = the second word of the selectedChunk to the 
fourth word of the selectedChunk
       put the textStyle of char myChar of field "text" into myRepeat
       replace myStyle & "," with "" in myRepeat
       replace myStyle with "" in myRepeat
       set the textstyle of char myChar of field "text" to myRepeat
     end repeat
end mouseUp

note:
I tried the "for each char" loop, but it was not applicable the way i 
used it. (it provided always the character, but no number or other 
location possibility)
for better reading copy to a button and tab on each line.
for use set the traversalon to false

hope you find something faster...