[gcmalloc]

useless use of cat

    pv < "$1" > "$2"

[nitrogen]

Even if the cat at the beginning of a pipe isn't strictly necessary, it still helps readability to have everything flowing from left to right.

[emillon]

I also advocate this "useless" use of cat, but you can write the redirection before the command:

    <"$1" pv >"$2"

[michaelmior]

The bigger problem is that using cat destroys the file size information.

[nilved]

pv reads content from a file by default, so that can actually be reduced further to:

    pv "$1" > "$2"

[simcop2387]

Which will actually give better results this way, since it'll read the size of the file and use that to provide an estimate even.