Recently cached image:

$ ./wrk -t12 -c400 -d30s http://127.0.0.1:5000/twolfson
Running 30s test @ http://127.0.0.1:5000/twolfson
  12 threads and 400 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency   133.19ms   13.20ms 196.88ms   80.69%
    Req/Sec   246.66     38.60   390.00     66.95%
  88688 requests in 30.01s, 2.75GB read
Requests/sec:   2955.50
Transfer/sec:     93.98MB
Uncached image:

$ ./wrk -t12 -c400 -d30s http://127.0.0.1:5000/twolfson
Running 30s test @ http://127.0.0.1:5000/twolfson
  12 threads and 400 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    16.34s    13.54s   28.56s    59.20%
    Req/Sec   354.65    202.30     1.11k    66.01%
  69391 requests in 30.01s, 2.15GB read
  Socket errors: connect 0, read 0, write 0, timeout 3835
Requests/sec:   2312.11
Transfer/sec:     73.52MB