Via [url=http://blog.counter-strike.net/index.php/2018/05/20410/]the CS:GO blog[/url]:

[quote=Valve][ MISC ]
– Fixed stability issue for physics collision detection against displacement surfaces.
– Fixed some situations in which stickers would not appear properly on weapons in-game.
– Fixed an issue where MP3’s embedded in maps wouldn’t work. (Thanks to Steam user MajesticCatDog for help in diagnosing this issue).
– Removed legacy audio cache commands.

[ SDK ]
– When loading the map in development mode with “developer 1” enabled, engine will display DISP_VPHYSICS warnings for displacements with degenerate collision faces. When such displacement faces are encountered, the entire displacement object will have no collision in-game. Additional clip brushes or adjustments to such displacements may be added by map authors in these cases.[/quote]

Rumor has it:

- /u/vMcJohn [url=https://www.reddit.com/r/GlobalOffensive/comments/8h3638/counterstrike_global_offensive_update_for_5418/dygu218/?context=1]provided a little more detail on the physics stability issue that got fixed[/url]

- [url=https://github.com/SteamDatabase/GameTracking-CSGO/commit/3e62217a7e18af8297561a23594d4eb80f167d93]The "snd_disable_legacy_audio_cache" command and other legacy commands have been removed[/url] as no widespread issues were reported with streaming audio being made the default in the 4/30/18 (5/1/18 UTC) update

- Size is ~5 MB + ~430 KB (for the SDK)