diff --git a/.changeset/reduce-client-bundle.md b/.changeset/reduce-client-bundle.md
new file mode 100644
index 000000000..b34978d5b
--- /dev/null
+++ b/.changeset/reduce-client-bundle.md
@@ -0,0 +1,5 @@
+---
+"gitbook": patch
+---
+
+Reduce the JavaScript and CSS loaded on published site pages: the search index and its UI now load only when search is opened, the admin toolbar and OpenAPI/ContentKit styles are no longer shipped to every visitor, and the client bundle targets modern browsers.