How to read/write a string from/to file fast

When I'm debugging large SQL inserts/updates I tend to use the following two functions

const
  szChar = SizeOf(Char);
/// 

///   saves a string to a file
/// 
procedure StringToFile(const s: string; const FileName: string);
var
  FileStream: TFileStream;
begin
  FileStream := TFileStream.Create(FileName, fmCreate);
  try
    FileStream.WriteBuffer(Pointer(s)^, (Length(s) * szChar));
  finally
    FreeAndNil(FileStream);
  end; // try
end;

/// 

///   returns the content of the file as a string
/// 
function StringFromFile(const FileName: string): string;
var
  FileStream: TFileStream;
begin
  FileStream := TFileStream.Create(FileName, fmOpenRead);
  try
    SetLength(Result, (FileStream.Size div szChar));
    FileStream.ReadBuffer(Pointer(Result)^, FileStream.Size);
  finally
    FreeAndNil(FileStream);
  end; // try
end;

this functions are pretty fast and you can easily find other usage for them.