if you have multiple columns and want to calculate the differences in seconds and milliseconds, a query like this can help to produce output like in the csv file in this gist.
This is the query
select
"timestamp"
,strftime('%f',julianday("inserted")-julianday("timestamp")) "Timestamp to inserted"
,strftime('%f',julianday("response_calculated")-julianday("inserted")) "Response calculated"
,strftime('%f',julianday("response_timestamp")-julianday("response_calculated")) "API Call finished"
from queue
order by timestamp