docs: Mention perf improvement in v9.14 blog (#658)

src/content/blog/2024-11-01-eslint-v9.14.0-released.md

@@ -40,7 +40,11 @@ const regex2 = /^[a-z](?-i:[a-z])$/i;
 
 The updates in ESLint include parsing and ensuring that rules related to regular expressions are behaving as expected.
 
+### Improved configuration file lookup performance
 
+In v9.13.0, we introduced changes to how configuration files were looked up. Some of these changes negatively impact ESLint's runtime performance due to incorrect caching of configuration file data. This was visible primarily using the default configuration lookup algorithm, where a [20-30% performance degradation was reported](https://github.com/eslint/eslint/issues/19025) (the new algorithm, accessed via `--flag unstable_config_lookup_from_file`, has different performance characteristics and didn't show the same negative performance impact in our tests).
+
+We've now fixed the configuration file lookup caching behavior both in the default algorithm and the experimental algorithm so you should improved performance when you upgrade from v9.13.0.