The data on data.stackexchange.com is "cached"; the data sets are updated once every week. Queries are not done against the live SE databases. See the data.se.com FAQdata.se.com FAQ:
How frequently is Stack Exchange Data Explorer updated?
The data is updated early every Sunday morning around 3:00 UTC.
Query results are cached until the next dataset update, as the result of any one query and parameter combination is not going to change until then anyway.