HUNCHENTOOT:SEND-HEADERS and streaming output vs. FLEX:WITH-OUTPUT-TO-SEQUENCE

ht:s-h__vs__flex:w-o-t-s.md

-             (let ((stream (hunchentoot:send-headers)))
+             (flex:with-output-to-sequence (stream)

and a short benchmark (wrk --latency -c2 -t2 -d 5)

gives these results. First HT:S-H:

...
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    24.07ms   14.31ms  48.32ms   61.35%
    Req/Sec    41.39      9.00    60.00     66.00%
  Latency Distribution
     50%   13.69ms
     75%   41.81ms
     90%   43.92ms
     99%   45.02ms
  414 requests in 5.01s, 700.10KB read
Requests/sec:     82.67
Transfer/sec:    139.81KB

With this single change to FLEX:W-O-T-S:

  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     7.95ms    2.69ms  30.98ms   92.86%
    Req/Sec   128.36     14.32   150.00     80.00%
  Latency Distribution
     50%    7.17ms
     75%    7.46ms
     90%    8.98ms
     99%   20.48ms
  1280 requests in 5.00s, 2.09MB read
Requests/sec:    255.76
Transfer/sec:    427.85KB

Seems that in the former case (nearly) each individual byte gets its own HTTP chunk...