Opening pages before the click

Settings → Open Pages Before the Click decides when a visitor's browser starts loading the page they are about to open. Browsers that read speculation rules, Chrome and Edge among them, fetch the page ahead of the click, so it opens at once; a browser that does not read them ignores them. Start loading a page offers three choices:

• When the pointer rests on its link: once the pointer has rested on a link for a moment. A page NimbleCache has cached costs a file read, so fetching it early is cheap, and this is the choice that makes the most difference.
• When its link is pressed (WordPress's default): as the mouse button or a finger goes down, a moment before the click. WordPress 6.8 and later do this on every site; NimbleCache leaves out the pages below.
• Only once its link is clicked: nothing is fetched early, WordPress's own fetching included.

Whichever you choose, a page NimbleCache never caches is never fetched early: the cart, the checkout and the account pages and everything under them (the order received page, each account tab), the Easy Digital Downloads checkout and receipts, every line of Rules → Excluded URLs and of the older Excluded URLs setting (except a line written as a regular expression, which the cache still refuses), the pages and categories under Excluded pages, and search results and feeds while they are not cached. WordPress already leaves out any address with a query, its own files and folders, links marked nofollow and links with the no-prefetch class. On a network of sites in folders, a site also leaves out the other sites' folders inside its own: their pages are theirs.

Nobody signed in is given any of it, as WordPress decides, and nor is a visitor the cache does not serve: a shopper with something in their cart, or a visitor whose cookie or browser your Rules exclude. Every page fetched early for them would be a page built for them. If a shopper adds a product without leaving a cached page, a small script takes the rules out of that page as soon as the cart's cookie appears. With plain permalinks nothing is fetched early, as WordPress decides.

Resting on a link fetches pages early only while every page can be cached. With caching off, or with Rules → Cache on set to some kinds of page only, NimbleCache cannot tell those pages from their addresses, so pages are fetched as their link is pressed instead, and the Settings screen says so. The same happens on the main site of a network with more than 100 sites in its folder. NimbleCache never asks for a page to be prerendered: that runs the page, its analytics included, for a visit nobody made.

The rules are part of every stored page, so changing the choice empties the cache, and the Clearing Log says "Open pages before the click changed".

A new site starts with WordPress's default. A site that had NimbleCache before keeps what its visitors' browsers already did: WordPress's default on WordPress 6.8 and later, and nothing before that. The Dashboard offers When the pointer rests on its link once, with Switch it on and No thanks; choosing anything on the Settings screen answers it too. WordPress before 6.8 has no speculative loading of its own, so there NimbleCache prints the same rules itself. Where the Speculative Loading plugin from WordPress's performance team is active, that plugin is in charge: the Settings screen says so, and NimbleCache changes nothing. If your host has changed WordPress's own default (the WP_SPECULATIVE_LOADING_DEFAULT_MODE and _EAGERNESS settings of WordPress 7.1), When its link is pressed keeps the host's choice.