enhance: avoid creating duplicate buffers

[ardatan]

No description provided.

[github-actions]

🚀 Snapshot Release (alpha)

The latest changes of this PR are available as alpha on npm (based on the declared changesets):

Package	Version	Info
@whatwg-node/node-fetch	0.4.13-alpha-20230821132128-700c49e	npm ↗︎ unpkg ↗︎
@whatwg-node/server	0.9.11-alpha-20230821132128-700c49e	npm ↗︎ unpkg ↗︎

[github-actions]

✅ Benchmark Results

     ✓ no-errors
     ✓ expected-result

     checks.........................: 100.00% ✓ 362042      ✗ 0     
     data_received..................: 36 MB   1.2 MB/s
     data_sent......................: 15 MB   483 kB/s
     http_req_blocked...............: avg=1.22µs   min=799ns    med=1µs     max=6.69ms   p(90)=1.4µs    p(95)=1.7µs   
     http_req_connecting............: avg=0ns      min=0s       med=0s      max=123.59µs p(90)=0s       p(95)=0s      
     http_req_duration..............: avg=106.99µs min=62.6µs   med=94.8µs  max=16.92ms  p(90)=123.1µs  p(95)=139.8µs 
       { expected_response:true }...: avg=106.99µs min=62.6µs   med=94.8µs  max=16.92ms  p(90)=123.1µs  p(95)=139.8µs 
     http_req_failed................: 0.00%   ✓ 0           ✗ 181021
     http_req_receiving.............: avg=17.8µs   min=9.4µs    med=16µs    max=10.88ms  p(90)=24.2µs   p(95)=26.6µs  
     http_req_sending...............: avg=5.6µs    min=3.7µs    med=4.4µs   max=9.85ms   p(90)=6µs      p(95)=7.9µs   
     http_req_tls_handshaking.......: avg=0s       min=0s       med=0s      max=0s       p(90)=0s       p(95)=0s      
     http_req_waiting...............: avg=83.58µs  min=46.8µs   med=73.59µs max=16.54ms  p(90)=96.9µs   p(95)=111.99µs
     http_reqs......................: 181021  6033.782879/s
     iteration_duration.............: avg=161.57µs min=104.79µs med=143.5µs max=21.63ms  p(90)=182.09µs p(95)=203.39µs
     iterations.....................: 181021  6033.782879/s
     vus............................: 1       min=1         max=1   
     vus_max........................: 1       min=1         max=1