Cold start in computing refers to a problem where a system or its part was created or restarted and is not working at its normal operation.
The problem can be related to initialising internal objects or populating cache or starting up subsystems.
In a typical web service system the problem occurs after restarting the server, and also when clearing the cache (e.g., after releasing new version).
Other services like a caching proxy or web accelerator will also need time to gather new resources and operate normally.
[5] Unlike the previous mentioned instances, cold starting in these scenarios can yield better results of the model.