When you creating a new web app (or web site, how it used to be called until recently) it’s have “Always On” setting off by default, which means the web site will be recycled after period of inactivity (20 minutes). This setting is somewhat similar to “Idle Time-out” setting on IIS application pool.When you web app is recycled, it will take Azure some time to bring it up the site when it’s accessed next time (in my experience it may take about 5-10 seconds) which could be frustrating for user. So enabling “Always On” setting on Azure web app increases application responsiveness, especially if application is not very frequently accessed by users.
However, this setting comes at cost. Although there is no additional cost for enabling “Always On” option itself, this option is not available on Free and Shared pricing tiers, it requires Basic or Standard pricing.
“Always On” setting is available though “Configure” tab on old portal and “Settings” -> “Application settings” blade on a new (preview) portal.
How exactly does it work? Thanks.