In Swfit Performance there are 2 type of cache expiry: Time based mode and Action based mode
Action based (recommended)
If you set Cache expiry to Action Based, Swift Performance will take care of cache expiration. If you modify anything – edit post, stock has been changed, etc.- cache will be cleared for all pages where it is necessary: single page, archive pages, feeds, etc.
Time based mode is working on the same way as Action based, however when cache expired, the cache will be cleared, even if no modifications has been made.
Which method should I use?
By default we recommend to use Action based mode for the best experience and results. However depending on the active theme and plugins you may have to use Time based mode.
WordPress is using nonces to validate requests from authenticated users, so using nonce for not logged in user is not necessary at all. Unfortunately many themes & plugins (even popular ones) are misusing WordPress nonce (some of them are even using nonce for login…) and expired nonce can cause functionality issues. WordPress nonce is valid for maximum 24 hours, but it may will be invalid after 12 hours.
If you have a contact page, which contains a contact form which is using nonce, then you can use Action Based mode, and add the contact page to Short Lifespan Pages. However if all pages contains the contact form in the footer, you have to use Time Based mode.
Short Lifespan Pages
Here you can add pages which are using nonce and should be cleared in every 12 hours
Cache Expiry Time
For Time based mode you can set Cache expiry time (it can be minimum 30 mins, maximum 2days)
Garbage Collection Interval
Swift Performance will use cronjobs to check expired cache. Garbage collection interval means, Swift Performance will check cache expiry at set times.