thanks for this suggestion.

Gave it a try and wohoooooo!

no freeze!!

The trade-off it seems is the time it takes to load the entire file though.
I took out the stop-watch and used the same 140000 line file and it took 30 minutes and 30 seconds for all the lines to load up.

Not being one to give up. I tried to manipulate the time using -m flag, which made no difference. Then it occurred to me that instead of using fopen/fread/fclose, why not use the timer on loadbuf and load it up incrementally.

and it works. No freeze whatsoever and the time it takes to load up a 140000 file is 26 minutes & 20 seconds.- small improvement. This is loading up 50 lines at a time.

Now I'm trying to work out what would be the optimum way of incrementally loading up using loadbuf, ie would modifying how many lines per increment make a difference, also would adding a small delay help improve clear memory (assuming its a memory issue?) , eg if timer were set to do after 1 or 2 seconds rather than immediate - would this improve performance.

BTW i did this crude change to the code you posted

Code:
 
alias addline {
  /loadbuf %x $+ - $+ %y -o big 1 file.txt
  inc %x 50
  inc %y 50
 }


then typed this instead:

//dialog -m big big | set %x 1 | set %y 50 | .timeraddline 3000 0 addline