Reasons why ChessKISS 64 is slower than 32, part 2

 While debugging I've found this, quite interesting...

Search.pas.898: if board.LastPieceCaptured <> nil then //same value and index
0000000000615F3D 488B8338040000   mov rax,[rbx+$00000438]
0000000000615F44 90               nop
0000000000615F45 4885C0           test rax,rax
0000000000615F48 745D             jz $0000000000615fa7
Search.pas.900: recaptures[side] := board.LastPieceCaptured.GetMiddleValue + TMoveHelper.GetTo(aMove);
0000000000615F4A 488B8338040000   mov rax,[rbx+$00000438]

LastPieceCaptured is loaded into RAX, the pointer is valid, thus I'm going to use it, but again the compiler is loading the same value into the same register, what about the NOP operation in between?