user20949: I remark that whatever the level of the Lichess' Stockfish I choose it plays in average at the same speed. How could I tune my Stockfish (the one I use in Fritz or Arena) to achieve the same with the same performance ?

user15415: The settings used for the Stockfish levels on lichess can be found at https://github.com/niklasf/fishnet/blob/53e218bd184554265748513f85d19e601f18c310/fishnet.py#L117-L119:
LVL_SKILL = [0, 3, 6, 10, 14, 16, 18, 20]
LVL_MOVETIMES = [50, 100, 150, 200, 300, 400, 500, 1000]
LVL_DEPTHS = [1, 1, 2, 3, 5, 8, 13, 22]

where LVL_SKILL refers to the Skill Level UCI option in Stockfish, LVL_MOVETIMES to the maximum move time in milliseconds, and LVL_DEPTHS to the maximum depth for each of the eight levels.
The move time and depth might not be easy to set in a local GUI, but you can simply use the Skill Level option to adjust playing strength where 20 means best play and 0 is the lowest available level for Stockfish.

20949: <p>I remark that whatever the level of the Lichess' Stockfish I choose it plays in average at the same speed. How could I tune my Stockfish (the one I use in Fritz or Arena) to achieve the same with the same performance ?</p>
 15415: <p>The settings used for the Stockfish levels on lichess can be found at <a href="https://github.com/niklasf/fishnet/blob/53e218bd184554265748513f85d19e601f18c310/fishnet.py#L117-L119" rel="noreferrer">https://github.com/niklasf/fishnet/blob/53e218bd184554265748513f85d19e601f18c310/fishnet.py#L117-L119</a>:</p>

<pre><code>LVL_SKILL = [0, 3, 6, 10, 14, 16, 18, 20]
LVL_MOVETIMES = [50, 100, 150, 200, 300, 400, 500, 1000]
LVL_DEPTHS = [1, 1, 2, 3, 5, 8, 13, 22]
</code></pre>

<p>where <code>LVL_SKILL</code> refers to the <code>Skill Level</code> UCI option in Stockfish, <code>LVL_MOVETIMES</code> to the maximum move time in milliseconds, and <code>LVL_DEPTHS</code> to the maximum depth for each of the eight levels.</p>

<p>The move time and depth might not be easy to set in a local GUI, but you can simply use the <code>Skill Level</code> option to adjust playing strength where 20 means best play and 0 is the lowest available level for Stockfish.</p>
