You have to specify the time for each frame using ImageDelayTime[] property. Example:
var
  i:integer;
begin
  // set time for each frame
  for i:=0 to ImageEnMView1.ImageCount-1 do
    ImageEnMView1.ImageDelayTime[i] := 100;  // 100 milliseconds
  // now play
  ImageEnMView1.Playing := SpeedButton1.Down;
end;