2 files changed, 39 insertions, 6 deletions

diff --git a/src/viewport.cpp b/src/viewport.cpp
index cb0b36f40..6e7dfc495 100644
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -88,6 +88,7 @@
 #include "command_func.h"
 #include "network/network_func.h"
 #include "framerate_type.h"
+#include "core/sort_func.hpp"
 
 #include <map>
 
@@ -1379,11 +1380,22 @@ static bool ViewportSortParentSpritesChecker()
 	return true;
 }
 
+static int CDECL CompareParentSprites(ParentSpriteToDraw * const *psd, ParentSpriteToDraw * const *psd2)
+{
+	const ParentSpriteToDraw *ps = *psd;
+	const ParentSpriteToDraw *ps2 = *psd2;
+	return ps->xmin - ps2->xmin;
+}
+
 /** Sort parent sprites pointer array */
 static void ViewportSortParentSprites(ParentSpriteToSortVector *psdv)
 {
 	ParentSpriteToDraw **psdvend = psdv->End();
 	ParentSpriteToDraw **psd = psdv->Begin();
+
+	/* pre-sort by xmin in ascending order */
+	QSortT(psd, psdvend - psd, CompareParentSprites);
+
 	while (psd != psdvend) {
 		ParentSpriteToDraw *ps = *psd;
 
@@ -1420,9 +1432,11 @@ static void ViewportSortParentSprites(ParentSpriteToSortVector *psdv)
 				 * I.e. every single order of X, Y, Z says ps2 is behind ps or they overlap.
 				 * That is: If one partial order says ps behind ps2, do not change the order.
 				 */
-				if (ps->xmax < ps2->xmin ||
-						ps->ymax < ps2->ymin ||
-						ps->zmax < ps2->zmin) {
+				if (ps->xmax < ps2->xmin) {
+					/* all following sprites have xmin >= ps2->xmin */
+					break;
+				}
+				if (ps->ymax < ps2->ymin || ps->zmax < ps2->zmin) {
 					continue;
 				}
 			}
diff --git a/src/viewport_sprite_sorter_sse4.cpp b/src/viewport_sprite_sorter_sse4.cpp
index 05a7f8aa1..e685fff57 100644
--- a/src/viewport_sprite_sorter_sse4.cpp
+++ b/src/viewport_sprite_sorter_sse4.cpp
@@ -15,6 +15,7 @@
 #include "cpu.h"
 #include "smmintrin.h"
 #include "viewport_sprite_sorter.h"
+#include "core/sort_func.hpp"
 
 #include "safeguards.h"
 
@@ -25,12 +26,24 @@
 	#define LOAD_128 _mm_loadu_si128
 #endif
 
+static int CDECL CompareParentSprites(ParentSpriteToDraw * const *psd, ParentSpriteToDraw * const *psd2)
+{
+	const ParentSpriteToDraw *ps = *psd;
+	const ParentSpriteToDraw *ps2 = *psd2;
+	return ps->xmin - ps2->xmin;
+}
+
 /** Sort parent sprites pointer array using SSE4.1 optimizations. */
 void ViewportSortParentSpritesSSE41(ParentSpriteToSortVector *psdv)
 {
-	const __m128i mask_ptest = _mm_setr_epi8(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  0,  0,  0,  0);
+	const __m128i mask_ptest  = _mm_setr_epi8(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  0,  0,  0,  0);
+	const __m128i mask_ptest2 = _mm_setr_epi8(-1, -1, -1, -1,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0);
 	ParentSpriteToDraw ** const psdvend = psdv->End();
 	ParentSpriteToDraw **psd = psdv->Begin();
+
+	/* pre-sort by xmin in ascending order */
+	QSortT(psd, psdvend - psd, CompareParentSprites);
+
 	while (psd != psdvend) {
 		ParentSpriteToDraw * const ps = *psd;
 
@@ -64,8 +77,14 @@ void ViewportSortParentSpritesSSE41(ParentSpriteToSortVector *psdv)
 			__m128i ps1_max = LOAD_128((__m128i*) &ps->xmax);
 			__m128i ps2_min = LOAD_128((__m128i*) &ps2->xmin);
 			__m128i rslt1 = _mm_cmplt_epi32(ps1_max, ps2_min);
-			if (!_mm_testz_si128(mask_ptest, rslt1))
-				continue;
+			if (!_mm_testz_si128(mask_ptest, rslt1)) {
+				if (!_mm_testz_si128(mask_ptest2, rslt1) /* ps->xmax < ps2->xmin */) {
+					/* all following sprites have xmin >= ps2->xmin */
+					break;
+				} else {
+					continue;
+				}
+			}
 
 			__m128i ps1_min = LOAD_128((__m128i*) &ps->xmin);
 			__m128i ps2_max = LOAD_128((__m128i*) &ps2->xmax);