diff --git a/source/blender/render/intern/source/rendercore.c b/source/blender/render/intern/source/rendercore.c
index 7ba81f60154..1489664b414 100644
--- a/source/blender/render/intern/source/rendercore.c
+++ b/source/blender/render/intern/source/rendercore.c
@@ -158,7 +158,7 @@ float mistfactor(float *co)	/* dist en height, return alpha */
 		}
 	}
 
-	return 1.0-fac;
+	return (1.0-fac)* (1-R.wrld.misi);	
 }
 
 void RE_sky(char *col)
@@ -1052,8 +1052,10 @@ void scanlinehaloPS(unsigned int *rectz, long *rectdelta, unsigned int *rectt, s
 		if((a & 255)==0) har= R.bloha[a>>8];
 		else har++;
 
-		if(RE_local_test_break() ) break;
-		
+		if( !(a % 256) && RE_local_test_break() ) break;  /* Hos, RPW - fix slow render bug, */
+													/* !(loopvar%256) keeps checking for */
+													/* ESC too often and bogging down render */
+													/* (Based on discovery by Rob Haarsma) */
 		if(ys>har->maxy);
 		else if(ys<har->miny);
 		else {
@@ -1159,7 +1161,7 @@ void scanlinehalo(unsigned int *rectz, unsigned int *rectt, short ys)
 		if((a & 255)==0) har= R.bloha[a>>8];
 		else har++;
 
-		if(RE_local_test_break() ) break; 
+		if( !(a % 256) && RE_local_test_break() ) break; /* Hos, RPW, fixes Slow Render Bug */
 
 		if(ys>har->maxy);
 		else if(ys<har->miny);
@@ -1213,7 +1215,7 @@ void halovert()
 		if((a & 255)==0) har= R.bloha[a>>8];
 		else har++;
 
-		if(RE_local_test_break() ) break; 
+		if( !(a % 256) && RE_local_test_break() ) break; /* Hos, RPW, fixes slow render bug */
 
 		if(har->maxy<0);
 		else if(R.recty<har->miny);
@@ -1267,7 +1269,7 @@ void halovert()
 					rectt+= R.rectx;
 					rectz+= R.rectx;
 					
-					if(RE_local_test_break() ) break; 
+					if( !(y % 256) && RE_local_test_break() ) break; /* Hos,RPW, Fixes slow render bug */
 				}
 
 			}
@@ -2475,7 +2477,7 @@ void zbufshadeDA(void)	/* Delta Accum Pixel Struct */
 			/* 1 is for osa */
 		if(R.r.mode & R_EDGE) edge_enhance();
 		
-		if(RE_local_test_break()) break;
+		if( !(v % 256) && RE_local_test_break()) break; /*Hos,RPW, fixes slow render bug*/
 	}
 	if(R.flag & (R_ZTRA+R_HALO) ) {	 /* to get back correct values of zbuffer Z for transp and halos */
 		xd= jit[0][0];
@@ -2607,7 +2609,7 @@ void zbufshadeDA(void)	/* Delta Accum Pixel Struct */
 			}
 			rz+= R.rectx;
 		}
-		if(RE_local_test_break()) break; 
+		if(!(y % 256) && RE_local_test_break()) break; /* Hos,RPW, fixes slow render bug */
 	}
 
 	if( (R.r.mode & R_EDGE) && RE_local_test_break()==0) {
@@ -2706,7 +2708,7 @@ void zbufshade(void)
 									R.rectot);
 		}
 		
-		if(RE_local_test_break()) break; 
+		if(!(y % 256) && RE_local_test_break()) break; /*Hos,RPW, Fixes Slow render bug */
 	}
 
 	if(R.flag & R_ZTRA) endaccumbuf();
@@ -2769,7 +2771,7 @@ void renderhalo(HaloRen *har)	/* postprocess version */
 	
 				rectt+= R.rectx;
 				
-				if(RE_local_test_break()) break; 
+				if( !(y % 256) && RE_local_test_break()) break; /* Hos,RPW, fixes slow render bug */
 			}
 	
 		}