Maybe the problem is too much memory, so Windows start swaping VFP memory. Try to limit the memory with SYS(3050). You can also try to issue FFLUSH() comman every few thousand records.

>(VFP 7 SP1 on Windows 2000 or Windows XP pro)
>
>I have to perform 3 operation on a text file.
>
>1 - read a line from a text file.
>2 - perform some operations on the string.
>3 - write the line in another file.
>
>The text file was really big (950 mb).
>
>The program run fast for the first ~50 mb but after that it start to slow down (crawl).
>The computer have 1 gb of memory an 100 gb of available disk space.
>From the task manager I can see that only around 200 mb was used during the operation.
>
>What is the best way to open the files? buffered/unbuffered?
>Flush when I reach a certain point in the file? every 10 mb?
>How can I optimize the process to use all available memory and speed up the process? some sys() function to use?
>
>TIA :-)