reading from / writing to file : 2 dumb questions

[jbv at souslelogo.com]

Hi list

I am trying to improve the speed of a large script including
many loops.
Could anyone explain why :

- question 1 : if a text file contains "toto", after running the
following lines
   open file tpath
   read from file tpath until EOF
   write (it & return & "titi") to file tpath
   close file tpath

the file contains :
  totototo
  titi

and when running these lines
   open file tpath
   read from file tpath until EOF
   close file tpath
   open file tpath
   write (it & return & "titi") to file tpath
   close file tpath

the file contains :
   toto
   titi


- question 2

why is this line
  put "toto" after URL ("binfile:/hd/myFile.txt")

much slower than
         open file tpath
         read from file tpath until EOF
         close file tpath
         open file tpath
         write (it & return & "toto") to file tpath
         close file tpath

Thanks in advance.
jbv