Attempt to fix lag/client crashes with a ParticleManager msg blocker

Co-authored-by: tilgep <tilgep95@gmail.com>

Author: Vauff

cfg/cs2fixes/cs2fixes.cfg

@@ -24,6 +24,7 @@ cs2f_prevent_using_players		0		// Whether to prevent +use from hitting players (
 cs2f_map_steamids_enable		0		// Whether to make Steam ID's available to maps
 cs2f_fix_game_bans				0		// Whether to fix CS2 game bans spreading to all new joining players
 cs2f_free_armor					0		// Whether kevlar (1+) and/or helmet (2) are given automatically
+cs2f_block_particle_msgs		0		// Whether to block CUserMsg_ParticleManager messages to fix lag/crashes, experimental
 
 cs2f_beacon_particle			"particles/cs2fixes/admin_beacon.vpcf" // .vpcf file to be precached and used for player beacon
 cs2f_motd_url					""		// Server MOTD URL, shows up as a "Server Website" button in scoreboard

src/cs2fixes.cpp

@@ -661,6 +661,8 @@ void CS2Fixes::Hook_GameServerSteamAPIActivated()
 	RETURN_META(MRES_IGNORED);
 }
 
+CConVar<bool> g_cvarBlockParticleMsgs("cs2f_block_particle_msgs", FCVAR_NONE, "Whether to block CUserMsg_ParticleManager messages to fix lag/crashes, experimental", false);
+
 void CS2Fixes::Hook_PostEvent(CSplitScreenSlot nSlot, bool bLocalOnly, int nClientCount, const uint64* clients,
 							  INetworkMessageInternal* pEvent, const CNetMessage* pData, unsigned long nSize, NetChannelBufType_t bufType)
 {
@@ -789,6 +791,13 @@ void CS2Fixes::Hook_PostEvent(CSplitScreenSlot nSlot, bool bLocalOnly, int nClie
 			*(uint64*)clients &= ~silenceSoundMask;
 		}
 	}
+	else if (info->m_MessageId == UM_ParticleManager)
+	{
+		// These messages were previously unused, but recently started being used for weapon particles in the AG2 update
+		// Unfortunately, this new system seems extremely unoptimized for 64 players, and was causing severe performance issues & vector overflow client crashes
+		if (g_cvarBlockParticleMsgs.Get())
+			*(uint64*)clients = 0;
+	}
 }
 
 void CS2Fixes::AllPluginsLoaded()