perf: skip redundant work in RouteCollection::create() during route registration #10617

Problem

Without route caching, the route table is rebuilt on every request. Each $routes->get() (or post(), add(), and so on) runs RouteCollection::create(), which costs about 1.9 µs per route. That's about 8 times more than the worst-case cost of matching a route.

Two steps in create() do work that is usually wasted:

• The placeholder loop. create() runs str_ireplace(':' . $tag, ...) once for every registered placeholder (6 by default), even when $from has no : and nothing can match. That costs about 0.50 µs per route.
• helper('array'). It's called on every create(). RouteCollection no longer uses any array-helper function, but the call still loads the helper for the app as a side effect. Repeat calls cost about 0.24 µs per route.

Measurements

PHP 8.3 on macOS, OPcache on, production mode, warm. Config construction cost was turned off to approximate the state after #10615. The routes are a realistic mix: a third static, a third with one placeholder, a third with two, spread across groups.

Here's the cost breakdown of one $routes->get() call:

Proposal

1. In create(), run the placeholder loop only when the route key contains :. If it has no :, no str_ireplace can match, and no replacement can add a :. So the output is identical. That includes custom placeholders whose patterns contain :, such as (?:...).
2. Call helper('array') only on the first create() of each collection, using a private flag. The helper still loads at the same point as today, so apps that quietly depend on it keep working. A short comment will explain that the call stays only for this side effect.

Estimated savings are about 0.74 µs per route, roughly 40% of the build cost:

• 100 routes: about 75 µs per request
• 1000 routes: about 0.75 ms per request

Compatibility

• No change to public or protected APIs. The only new state is private.
• The route table comes out the same: same keys, handlers, names, and options.
• No changelog or upgrade-guide entry is planned.

Not changing

• esc() stays in create(). Apps can replace esc() in app/Common.php, so skipping the call would quietly bypass a custom version on route paths. A faster esc() for the html context could be a separate issue.
• The matcher (Router::checkRoutes()). A FastRoute-style matcher was prototyped. Without route caching, building its lookup structure on each request cost about as much as the linear scan it replaced. So the net gain was small at typical route counts.

Tests

Add cases to tests/system/Router/RouteCollectionTest.php that lock in today's behavior:

• A route with no placeholders keeps its exact key.
• A custom placeholder whose pattern contains (?:...), mixed with built-in placeholders, still expands correctly.

Run RouteCollectionTest.php and RouterTest.php.

Related

• perf: config classes check every property against the environment on each construction #10615: config construction cost
• perf: filter discovery tokenizes the app and system Config/Filters.php on every request #10616: filter discovery cost