如何提高两个String相加的速度

StringA := '';
LenA := 0;
MemLen := 10*1024;
Setlength(StringA, MemoLen);
While not Query1.Eof do
begin
  StringB := Query1.Fieldbyname('AField').AsStrimg;
  LenB := Length(StringB);
  if (LenA+LenB)>MemLen then
  begin
    MemLen := MemLen+10*1024;
    SetLength(StringA, MemLen);
  end;
  Move(StringB[1], StringA[LenA+1], lenB); 
  Inc(LenA, LenB);
  Query1.next;
end;
SetLength(StringA,LenA);