@Kozushi, unless you have a specific purpose for the long holds at the top, I don't recommend you do them.
I recommend you pick up the bar at whatever speed is natural - faster is better than slower, all other things being equal, but all other things must remain equal - you must still stay tight.
Pause briefly at the top, perhaps 1 second to "own" the lockout position, but then continue on with the rest of the movement. If you really want to practice time in the lockout position, I recommend you save that for the final rep of each set.
If you want the time under tension during lifting and lowering to be longer, put more weight on the bar - seriously. Deadlifting purposefully slowly might have a place in a hypertrophy-focused program, and it can certainly have a place to deal with certain deadlift issue. So can pausing at certain places in the movement, and so can doing only parts of the movement. But these are specific things for specific purposes - wait until your pull feels solid to you. In your case, I'd say something like 200 kg. And even then, you don't need fancy stuff, just pull.
-S-