Is jq internal sort slower than GNU sort?

Question

While filtering through this json file I did a benchmark and found out utilizing jq's internal sort and unique method is actually 25% slower than sort --unique!

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
jq "[.[].category] \| sort \| unique" channels.json	172.0 ± 2.6	167.8	176.8	1.25 ± 0.06
jq "[.[].category \| select((. != null) and (. != \"XXX\"))] \| sort \| unique" channels.json	151.9 ± 4.1	146.5	163.9	1.11 ± 0.06
jq ".[].category" channels.json \| sort -u	137.2 ± 6.6	131.8	156.6	1.00

Summary
  'jq ".[].category" channels.json | sort -u' ran
    1.11 ± 0.06 times faster than 'jq "[.[].category | select((. != null) and (. != \"XXX\"))] | sort | unique" channels.json'
    1.25 ± 0.06 times faster than 'jq "[.[].category] | sort | unique" channels.json'

test command:

hyperfine --warmup 3 \
    'jq "[.[].category] | sort | unique" channels.json'  \
    'jq "[.[].category | select((. != null) and (. != \"XXX\"))] | sort | unique" channels.json' \
    'jq ".[].category" channels.json | sort -u'

If we only test sort (without uniqueness), again jq is 9% slower than sort:

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
jq "[.[].category] \| sort" channels.json	133.9 ± 1.6	131.1	138.2	1.09 ± 0.02
jq ".[].category" channels.json \| sort	123.0 ± 1.3	120.5	125.7	1.00

Summary
  'jq ".[].category" channels.json | sort' ran
    1.09 ± 0.02 times faster than 'jq "[.[].category] | sort" channels.json'

versions:

jq-1.5-1-a5b5cbe
sort (GNU coreutils) 8.28

I expected using jq's internal functions would result in a faster processing than piping into an external app which itself should be spawned. Am I using jq poorly?

update Just repeated this experiment on host with FLASH storage, Arm CPU and these versions:

jq-1.6
sort (GNU coreutils) 8.32

result:

Benchmark #1: jq "[.[].category] | sort" channels.json
  Time (mean ± σ):     587.8 ms ±   3.9 ms    [User: 539.5 ms, System: 44.2 ms]
  Range (min … max):   582.8 ms … 594.2 ms    10 runs
 
Benchmark #2: jq ".[].category" channels.json | sort
  Time (mean ± σ):     606.0 ms ±   8.6 ms    [User: 569.5 ms, System: 49.0 ms]
  Range (min … max):   589.6 ms … 616.2 ms    10 runs
 
Summary
  'jq "[.[].category] | sort" channels.json' ran
    1.03 ± 0.02 times faster than 'jq ".[].category" channels.json | sort'

Now jq sort runs 3% faster than GNU sort :D