perf: fast-path interception route check and cache bot-detection regex

packages/next/src/server/lib/streaming-metadata.ts

@@ -4,16 +4,23 @@ import {
 } from '../../shared/lib/router/utils/is-bot'
 import type { BaseNextRequest } from '../base-http'
 
+// Cache compiled RegExp per pattern string to avoid re-creating it on every
+// request. The pattern comes from `nextConfig.htmlLimitedBots` which is a
+// static config value, so the cache will hold at most 1-2 entries.
+let cachedPattern: string | undefined
+let cachedRegex: RegExp | undefined
+
 export function shouldServeStreamingMetadata(
   userAgent: string,
   htmlLimitedBots: string | undefined
 ): boolean {
-  const blockingMetadataUARegex = new RegExp(
-    htmlLimitedBots || HTML_LIMITED_BOT_UA_RE_STRING,
-    'i'
-  )
+  const pattern = htmlLimitedBots || HTML_LIMITED_BOT_UA_RE_STRING
+  if (pattern !== cachedPattern) {
+    cachedPattern = pattern
+    cachedRegex = new RegExp(pattern, 'i')
+  }
   // Only block metadata for HTML-limited bots
-  if (userAgent && blockingMetadataUARegex.test(userAgent)) {
+  if (userAgent && cachedRegex!.test(userAgent)) {
     return false
   }
   return true

packages/next/src/shared/lib/router/utils/interception-routes.ts

@@ -11,7 +11,10 @@ export const INTERCEPTION_ROUTE_MARKERS = [
 export type InterceptionMarker = (typeof INTERCEPTION_ROUTE_MARKERS)[number]
 
 export function isInterceptionRouteAppPath(path: string): boolean {
-  // TODO-APP: add more serious validation
+  // Fast path: interception markers always start with '(' — skip the
+  // split + find for the vast majority of paths that have no parentheses.
+  if (!path.includes('(')) return false
+
   return (
     path
       .split('/')