perf(sort): Benchmark with a random 95MB file slow

Hi, uutils mainteners

i confirmed that the uu sort extremly a slow with 95MB file, as we did in the benchmark

relunsec@relunsec:~/software/coreutils/target/release$ cat /dev/urandom > random_data
^C
relunsec@relunsec:~/software/coreutils/target/release$ ls -lh random_data 
-rw-rw-r-- 1 relunsec relunsec 95M Jun 29 08:37 random_data
relunsec@relunsec:~/software/coreutils/target/release$ hyperfine --shell=none --warmup 3 "./sort random_data" "gnusort random_data"
Benchmark 1: ./sort random_data
  Time (mean ± σ):      5.487 s ±  0.040 s    [User: 6.048 s, System: 0.211 s]
  Range (min … max):    5.447 s …  5.566 s    10 runs
 
Benchmark 2: gnusort random_data
  Time (mean ± σ):      1.620 s ±  0.030 s    [User: 4.360 s, System: 0.138 s]
  Range (min … max):    1.581 s …  1.676 s    10 runs
 
Summary
  gnusort random_data ran
    3.39 ± 0.07 times faster than ./sort random_data
relunsec@relunsec:~/software/coreutils/target/release$ 

Start by reproducing the reported hyperfine comparison between ./sort random_data and gnusort using a similarly sized random file. Then locate the sort implementation and profile the workload to identify the source of the slowdown. Done means the cause is addressed and the benchmark is rerun to verify the performance change.