function MyTrunc(const V: Double): Integer; inline;
var
  D: Double;
begin
  if V > 0 then
    D := V - 0.499999999999 + $18000000000000
  else
    D := V + 0.499999999999 + $18000000000000;
  Result := PInteger(@D)^;
end;

procedure TForm1.Button6Click(Sender: TObject);
const
C = 100000000;
var
u: Extended;
I: Integer;
v, v1, v2: Integer;
t, t1, t2: Int64;
begin
u := Now;

t := GetTimestamp;
for I := 0 to C - 1 do
v := Trunc(u);
t := GetTimestamp - t;

t1 := GetTimestamp;
for I := 0 to C - 1 do
v1 := Round(u);
t1 := GetTimestamp - t1;

t2 := GetTimestamp;
for I := 0 to C - 1 do
v2 := MyTrunc(u);
t2 := GetTimestamp - t2;

ShowMessage(Format('Trunc: %dms, Round: %dms, MyTrunc: %dms'#13'%d, %d, %d',
[t, t1, t2, v, v1, v2]));
end;

function MyRound(const V: Double): Integer; inline;
var
  D: Double;
begin
  D := V + $18000000000000;
  Result := PInteger(@D)^;
end;