Simplifying away all the progressKey stuff gives exactly the same bench,
without any speed impact. Tested for speed against master with two benches
at depth 22 ran in parallel:
**testedpatch**
Total time (ms) : 92350
Nodes searched :
178962949
Nodes/second :
1937877
**master**
Total time (ms) : 92358
Nodes searched :
178962949
Nodes/second :
1937709
We also tested the patch at STC for no-regression with [-3, 1] bounds:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 57299 W: 11529 L: 11474 D: 34296
http://tests.stockfishchess.org/tests/view/
5b015a1c0ebc5914abc126e5
Closes https://github.com/official-stockfish/Stockfish/pull/1603
No functional change.