diff --git a/changelogs/4.0-snapshot.md b/changelogs/4.0-snapshot.md
index 03addc130..994eb594e 100644
--- a/changelogs/4.0-snapshot.md
+++ b/changelogs/4.0-snapshot.md
@@ -40,6 +40,8 @@ This major version features substantial changes throughout the core, including s
 - Lighting is no longer guaranteed to be available on every chunk. It's now calculated on the fly as-needed.
 - `/op`, `/deop`, `/whitelist add` and `/whitelist remove` no longer cause player data to be loaded from disk for no reason.
 - Timings now use high-resolution timers provided by `hrtime()` to collect more accurate performance metrics.
+- Z-order curves (morton codes) are now used for block and chunk coordinate hashes. This substantially improves performance in many areas by resolving a hashtable key hash collision performance issue. Affected areas include explosions, light calculation, and more.
+- [`libdeflate`](https://github.com/ebiggers/libdeflate) is now (optionally) used for outbound Minecraft packet compression. It's more than twice as fast as zlib in most cases, providing significant performance boosts to packet broadcasts and overall network performance.
 
 ### Logger revamp
 - Many components now have a dedicated logger which automatically adds [prefixes] to their messages.