diff --git a/SheepShaver/src/MacOSX/SheepShaver.xcodeproj/project.pbxproj b/SheepShaver/src/MacOSX/SheepShaver.xcodeproj/project.pbxproj
index be6efcae..f3b44dd7 100644
--- a/SheepShaver/src/MacOSX/SheepShaver.xcodeproj/project.pbxproj
+++ b/SheepShaver/src/MacOSX/SheepShaver.xcodeproj/project.pbxproj
@@ -1511,8 +1511,13 @@
 				);
 				COPY_PHASE_STRIP = YES;
 				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
+				GCC_AUTO_VECTORIZATION = YES;
+				GCC_DYNAMIC_NO_PIC = YES;
 				GCC_ENABLE_FIX_AND_CONTINUE = NO;
+				GCC_ENABLE_SSE3_EXTENSIONS = YES;
+				GCC_ENABLE_SUPPLEMENTAL_SSE3_INSTRUCTIONS = YES;
 				GCC_MODEL_TUNING = "";
+				GCC_OPTIMIZATION_LEVEL = 3;
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"DATADIR=",
 					HAVE_CONFIG_H,
@@ -1533,10 +1538,11 @@
 					../include,
 				);
 				INSTALL_PATH = /usr/local/lib;
+				"MACOSX_DEPLOYMENT_TARGET[arch=x86_64]" = 10.6;
 				PREBINDING = NO;
 				PRODUCT_NAME = kpx_cpu;
-				SDKROOT = "$(DEVELOPER_SDK_DIR)/MacOSX10.5.sdk";
-				"SDKROOT[arch=i386]" = "$(DEVELOPER_SDK_DIR)/MacOSX10.4u.sdk";
+				SDKROOT = "$(DEVELOPER_SDK_DIR)/MacOSX10.4u.sdk";
+				"SDKROOT[arch=x86_64]" = "$(DEVELOPER_SDK_DIR)/MacOSX10.6.sdk";
 				ZERO_LINK = NO;
 			};
 			name = Release;
@@ -1683,15 +1689,20 @@
 					x86_64,
 				);
 				COPY_PHASE_STRIP = YES;
+				DEAD_CODE_STRIPPING = NO;
 				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
+				GCC_AUTO_VECTORIZATION = YES;
 				GCC_CW_ASM_SYNTAX = NO;
-				GCC_DYNAMIC_NO_PIC = NO;
+				GCC_DYNAMIC_NO_PIC = YES;
 				GCC_ENABLE_FIX_AND_CONTINUE = NO;
 				GCC_ENABLE_PASCAL_STRINGS = NO;
+				GCC_ENABLE_SSE3_EXTENSIONS = YES;
+				GCC_ENABLE_SUPPLEMENTAL_SSE3_INSTRUCTIONS = YES;
 				GCC_ENABLE_SYMBOL_SEPARATION = NO;
 				GCC_ENABLE_TRIGRAPHS = NO;
 				GCC_INLINES_ARE_PRIVATE_EXTERN = NO;
 				GCC_MODEL_TUNING = G5;
+				GCC_OPTIMIZATION_LEVEL = 3;
 				GCC_PRECOMPILE_PREFIX_HEADER = NO;
 				GCC_PREFIX_HEADER = "";
 				GCC_PREPROCESSOR_DEFINITIONS = (
@@ -1721,7 +1732,7 @@
 				INFOPLIST_PREPROCESS = NO;
 				INSTALL_PATH = "$(HOME)/Applications";
 				MACOSX_DEPLOYMENT_TARGET = 10.4;
-				"MACOSX_DEPLOYMENT_TARGET[arch=x86_64]" = 10.5;
+				"MACOSX_DEPLOYMENT_TARGET[arch=x86_64]" = 10.6;
 				OTHER_CFLAGS = "";
 				OTHER_CPLUSPLUSFLAGS = "$(OTHER_CFLAGS)";
 				OTHER_LDFLAGS = (
@@ -1740,7 +1751,7 @@
 				PRECOMPS_INCLUDE_HEADERS_FROM_BUILT_PRODUCTS_DIR = NO;
 				PRODUCT_NAME = SheepShaver;
 				SDKROOT = "$(DEVELOPER_SDK_DIR)/MacOSX10.4u.sdk";
-				"SDKROOT[arch=x86_64]" = "$(DEVELOPER_SDK_DIR)/MacOSX10.5.sdk";
+				"SDKROOT[arch=x86_64]" = "$(DEVELOPER_SDK_DIR)/MacOSX10.6.sdk";
 				ZERO_LINK = NO;
 			};
 			name = Release;