note about sharp perf improvements

docs/docs/reference/release-notes/v2.30/index.md

@@ -13,6 +13,7 @@ Key highlights of this release:
 
 - [Query on Demand and Lazy Images: Generally available](#query-on-demand-and-lazy-images-generally-available) - improves `gatsby develop` bootup time
 - [Server Side Rendering (SSR) in development](#server-side-rendering-ssr-in-development) — helps you find and fix many build errors in development. We're starting a partial release of this feature to 5% of users.
+- [Image transformations up to 30% faster](#gatsby-plugin-sharp2120)
 - [gatsby-plugin-sass v3](#gatsby-plugin-sass300) - use the latest `sass-loader` and `Dart Sass` by default
 
 And several impactful updates in the new [`gatsby-plugin-image`](#gatsby-plugin-image050-beta) (beta):
@@ -92,6 +93,16 @@ See also:
 - https://github.com/gatsbyjs/gatsby/issues/27754
 - https://github.com/gatsbyjs/gatsby/pull/27991
 
+## [email protected]
+
+New approach to concurrency speeds up image transformations up to 30%.
+
+Previously we were applying several transformations to a single image concurrently.
+With the new approach we transform multiple images in parallel but apply transformations
+to each image serially.
+
+Another major change is [lazy images in develop](#query-on-demand-and-lazy-images-generally-available).
+
 ## [email protected] (beta)
 
 ### AVIF support