Speeding a handler?

[Ton Cardona]

I have a text field with 5.729 lines. 826 of them, those containing quotes, must appear coloured in red so the instruction would be:

put 0 into x
repeat for each line aLine of fld someFld
  add 1 to x
  if quote is in aLine then
    set the forecolor of line x of fld someFld to "red"
    replace quote with empty in line x of fld someFld
  end if
end repeat

The problem is it takes 55 seconds.

I have reduced this time to 33 seconds by recording previously the numbers of the lines to be coloured and storing them in a customProp, yet it still takes 33 seconds.

Does anyone know a faster way of performing this task?

Thanks in advance,

Ton