The optimized Python code seems to have a number of bugs:
The loop ending condition might miss non-handled `remaining` (when there is no new-line at the end of the file). (The fix should be simple. Just move the check one line below.)
When there is no newline in some chunk, it would handle the word incorrectly at the chunk boundaries. (But ok, with the constraint that lines cannot be longer than the chunk size, this should not happen. But this could have been fixed easily anyway. Just `remaining = chunk; continue` + the other fix.)
The loop ending condition might miss non-handled `remaining` (when there is no new-line at the end of the file). (The fix should be simple. Just move the check one line below.)
When there is no newline in some chunk, it would handle the word incorrectly at the chunk boundaries. (But ok, with the constraint that lines cannot be longer than the chunk size, this should not happen. But this could have been fixed easily anyway. Just `remaining = chunk; continue` + the other fix.)