I leave in France.
This morning response time was good.
Now at 12H34 France (UTC+1) speed degradation begins.
In reply to a message that contains embeded image I get a 4 second response time. This morning it was less than a second for the same message. Yesterday evening it was around 10 seconds.
:authority:
www.fastmail.com
:method:POST
ath:/api/?u=dca241af
:content-length:102944
...
Request send = 92 ms
Waiting = 3.99 s
The API scalability is not optimal.