Hold on -- if it really is "one lightweight SELECT per millisecond", and you're saying a select is "a couple hundred microseconds", say generously 200us?, then you're spending 200us out of every 1000us just selecting. That's a lot of polling!

I mean only in the same sense that you spend 1 second per second doing something. Time is probably not the best way to evaluate the resources this consumes and I doubt it takes much of anything else either.

It does seem weird though even for sqlite. I wonder how oban does it. I also wonder if OP knows oban can run on sqlite.