I don’t have any answers just an observation. When I usually see requests handled like that (the delays increasing with more steady requests) the first thing that comes to mind is soft throttling, the kind they might implement to stop abuse on the free plan. If there are no hard limits then I doubt they would spell out exactly where the ‘line’ is, but I am completely guessing.
I used anvil free for about a year before I had my company start paying for it and barely ran into issues.
By the time I needed to scale the business case for paying for it was already there.
Also, do you have two picos to test at the same time? (Or even another uplink running on another machine)
If it is throttling,
each uplink on the server side gets its own unique connection to anvil, so I don’t know if the suspected throttling would be shared across all connections, or just handled individually per device. Or again, if it would just go away on any of the not free plans.
I did run into throttling here, when I tried to make a Free-Tier csv to table uploader for new users:
If you want to clone it and see what I’m talking about, you can definitely make the servers very angry quickly by loading a large file and setting the processing to auto adjust the sever module timeout limit.