Pico-W: bad network throughput running as a webserver

[bablokb]

CircuitPython version

at least since 8.0.5

Code/REPL

see https://github.com/bablokb/circuitpython-examples/tree/master/webserver

Behavior

see below

Description

The example scenario runs a webserver. The main page sources a number of js and css-files. This triggers multiple parallel requests from the browser to the server. Total download size is about 140KB, throughputs (measured as total download time from within the browser development tools) are as follows:

• Pico-W (8.0.5 and 9.2.1): about 11s
• Pico Plus2 W: about 11s
• Adafruit Feather ESP32-S3 (4MB/2MB): about 1s

Additional information

This issue is opened on request of @eightycc, see #9826 (comment)

Searching the web for throughput figures for the Pico-W does not turn up many results. Some tests use iperf, but this is an artificial tool and does not test the given scenario. But maybe iperf could help to track down the cause. It seems there is a Python/MicroPython version available, so it might be worth a look.