Why isn't `\elapsedtime` of xetex on windows stable?

Question

% !TeX TS-program = xelatex
\documentclass{article}
\begin{document}
\ExplSyntaxOn
\tex_resettimer:D
\int_step_inline:nnn { 1 } { 1000 }
  {
    #1\tex_par:D
  }
\message{\fp_eval:n{\sys_timer:/65536}s}
\newpage
\tex_resettimer:D
\int_step_inline:nnn { 1 } { 1000 }
  {
    #1\tex_par:D
  }
\message{\fp_eval:n{\sys_timer:/65536}s}
\ExplSyntaxOff
\end{document}

Compiling this with texlive 2022, Windows 10 results in

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]
[17] [18] [19] [20] [21] 1.22698974609375s [22] [23] [24] [25] [26] [27]
[28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42]
[43] 0.037994384765625s [44]

The specific time value varies, but the first loop always costs about 30 times the one of the second loop.