diff --git a/engine/client/cl_demo.c b/engine/client/cl_demo.c
index 55c8b0dde..56b65994a 100644
--- a/engine/client/cl_demo.c
+++ b/engine/client/cl_demo.c
@@ -34,6 +34,7 @@ static qboolean lastdemowassystempath;
 
 extern cvar_t qtvcl_forceversion1;
 extern cvar_t qtvcl_eztvextensions;
+extern cvar_t record_flush;
 
 static unsigned char demobuffer[1024*66];	//input buffer
 static int demooffset;		//start offset of demo buffer
@@ -133,7 +134,8 @@ void CL_WriteDemoCmd (usercmd_t *pcmd)
 		VFS_WRITE (cls.demooutfile, &fl, 4);
 	}
 
-	VFS_FLUSH (cls.demooutfile);
+	if (record_flush.ival)
+		VFS_FLUSH (cls.demooutfile);
 }
 
 /*
@@ -196,7 +198,8 @@ void CL_WriteDemoMessage (sizebuf_t *msg, int payloadoffset)
 		VFS_WRITE(cls.demooutfile, net_message.data + payloadoffset, net_message.cursize - payloadoffset);
 		break;
 	}
-	VFS_FLUSH (cls.demooutfile);
+	if (record_flush.ival)
+		VFS_FLUSH (cls.demooutfile);
 }
 
 int demo_preparsedemo(unsigned char *buffer, int bytes)
@@ -948,7 +951,8 @@ void CL_WriteRecordDemoMessage (sizebuf_t *msg, int seq)
 
 	VFS_WRITE (cls.demooutfile, msg->data, msg->cursize);
 
-	VFS_FLUSH (cls.demooutfile);
+	if (record_flush.ival)
+		VFS_FLUSH (cls.demooutfile);
 }
 
 
@@ -974,7 +978,8 @@ void CL_WriteSetDemoMessage (void)
 	len = LittleLong(cls.netchan.incoming_sequence);
 	VFS_WRITE (cls.demooutfile, &len, 4);
 
-	VFS_FLUSH (cls.demooutfile);
+	if (record_flush.ival)
+		VFS_FLUSH (cls.demooutfile);
 }
 
 
diff --git a/engine/client/cl_main.c b/engine/client/cl_main.c
index 40a05a511..3a38ce81c 100644
--- a/engine/client/cl_main.c
+++ b/engine/client/cl_main.c
@@ -89,6 +89,7 @@ cvar_t	cl_serveraddress = CVARD("cl_serveraddress", "none", "The address of the
 cvar_t	qtvcl_forceversion1 = CVAR("qtvcl_forceversion1", "0");
 cvar_t	qtvcl_eztvextensions = CVAR("qtvcl_eztvextensions", "0");
 
+cvar_t	record_flush = CVARD("record_flush", "0", "If set, explicitly flushes demo data to disk while recording. This may be inefficient, depending on how your operating system is configured.");
 cvar_t cl_demospeed = CVARF("cl_demospeed", "1", 0);
 cvar_t	cl_demoreel = CVARFD("cl_demoreel", "0", CVAR_SAVE, "When enabled, the engine will begin playing a demo loop on startup.");
 
@@ -3760,6 +3761,7 @@ void CL_Init (void)
 	Cvar_Register (&w_switch,					cl_controlgroup);
 
 	Cvar_Register (&cl_demoreel,				cl_controlgroup);
+	Cvar_Register (&record_flush,					cl_controlgroup);
 
 	Cvar_Register (&cl_nofake,					cl_controlgroup);
 	Cvar_Register (&cl_chatsound,					cl_controlgroup);