diff --git a/uppsrc/CodeEditor/LogSyntax.cpp b/uppsrc/CodeEditor/LogSyntax.cpp
index 83ed0f126..674d74ed2 100644
--- a/uppsrc/CodeEditor/LogSyntax.cpp
+++ b/uppsrc/CodeEditor/LogSyntax.cpp
@@ -54,7 +54,7 @@ void LogSyntax::Highlight(const wchar *s, const wchar *end, HighlightOutput& hls
 		}
 		else {
 			bool hl = findarg(c, '[', ']', '(', ')', ':', '-', '=', '{', '}', '/', '<', '>', '*',
-			                     '#', '@', '\\', '.') >= 0
+			                     '#', '@', '\\', '.') >= 0;
 			hls.Put(1, hl ? hl_style[INK_OPERATOR] : ink);
 			s++;
 		}
diff --git a/uppsrc/Core/Stream.cpp b/uppsrc/Core/Stream.cpp
index f46d4062e..a0d7122cd 100644
--- a/uppsrc/Core/Stream.cpp
+++ b/uppsrc/Core/Stream.cpp
@@ -737,9 +737,6 @@ Stream& Stream::operator%(String& s) {
 				Get(); // reserved for future use... or removal
 			}
 		}
-		DDUMP(len);
-		DDUMP(GetPos());
-		DDUMP(GetSize());
 		if(IsError() || len + GetPos() > GetSize())
 			LoadError();
 		else {
diff --git a/uppsrc/ide/Builders/Build.cpp b/uppsrc/ide/Builders/Build.cpp
index 92eef6ec0..c25c0bdb3 100644
--- a/uppsrc/ide/Builders/Build.cpp
+++ b/uppsrc/ide/Builders/Build.cpp
@@ -155,6 +155,7 @@ One<Builder> MakeBuild::CreateBuilder(Host *host)
 	b->release_link = bm.Get("RELEASE_LINK", "");
 	b->script = bm.Get("SCRIPT", "");
 	b->main_conf = !!main_conf.GetCount();
+	b->allow_pch = bm.Get("ALLOW_PRECOMPILED_HEADERS", "") == "1";
 	return b;
 }
 
@@ -221,6 +222,7 @@ struct OneFileHost : Host {
 	virtual bool   Run(const char *cmdline, int slot, String key, int blitz_count) { return host->Run(cmdline, slot, key, blitz_count); }
 	virtual bool   Run(const char *cmdline, Stream& out, int slot, String key, int blitz_count) { return host->Run(cmdline, out, slot, key, blitz_count); }
 	virtual bool   Wait() { return host->Wait(); }
+	virtual bool   Wait(int slot) { return host->Wait(slot); }
 	virtual One<AProcess> StartProcess(const char *c) { return host->StartProcess(c); }
 	virtual void   Launch(const char *cmdline, bool) { host->Launch(cmdline); }
 	virtual void   AddFlags(Index<String>& cfg) { host->AddFlags(cfg); }
diff --git a/uppsrc/ide/Builders/Builders.h b/uppsrc/ide/Builders/Builders.h
index de6bdfbbf..ee9acd9d4 100644
--- a/uppsrc/ide/Builders/Builders.h
+++ b/uppsrc/ide/Builders/Builders.h
@@ -46,6 +46,7 @@ struct CppBuilder : Builder {
 	bool                   Run(const char *cmdline, int slot, String key, int blitz_count);
 	bool                   Run(const char *cmdline, Stream& out, int slot, String key, int blitz_count);
 	bool                   Wait();
+	bool                   Wait(int slot);
 	bool                   HasFlag(const char *f) const        { return config.Find(f) >= 0; }
 	bool                   Cp(const String& cmd, const String& package, bool& error);
 	bool                   Cd(const String& cmd);
diff --git a/uppsrc/ide/Builders/CppBuilder.cpp b/uppsrc/ide/Builders/CppBuilder.cpp
index e1aab53a3..d81f71b11 100644
--- a/uppsrc/ide/Builders/CppBuilder.cpp
+++ b/uppsrc/ide/Builders/CppBuilder.cpp
@@ -183,6 +183,11 @@ bool CppBuilder::Wait()
 	return host->Wait();
 }
 
+bool CppBuilder::Wait(int slot)
+{
+	return host->Wait(slot);
+}
+
 void CppBuilder::ChDir(const String& path)
 {
 	host->ChDir(path);
diff --git a/uppsrc/ide/Builders/MscBuilder.icpp b/uppsrc/ide/Builders/MscBuilder.icpp
index bc2b36f62..34dd8aac4 100644
--- a/uppsrc/ide/Builders/MscBuilder.icpp
+++ b/uppsrc/ide/Builders/MscBuilder.icpp
@@ -237,6 +237,38 @@ bool MscBuilder::BuildPackage(const String& package, Vector<String>& linkfile, S
 	Vector<String> sobjfile;
 	bool           error = false;
 
+	String pch;
+
+	if(allow_pch && pkg.GetCount() && IsMsc86()) {
+		String hdr_path = SourcePath(package, pkg[0]);
+		if(IsCHeaderFile(hdr_path) && HdependBlitzApproved(hdr_path)) {
+		// add check: .c in package should prohibit precompiled header
+		// add check: Only simple file name
+		// add check: Some file in package #includes it
+			int time = GetTickCount();
+			int slot = AllocSlot();
+			String pchfile = CatAnyPath(outdir, GetFileTitle(hdr_path) + ".pch");
+			String cppfile = ForceExt(hdr_path, ".$pch$.cpp");
+			SaveFile(cppfile, "#include \"" + pkg[0] + "\"\r\n");
+			if(slot < 0 ||
+			   !Run(Join(cc, cpp_options) + PdbPch(package, slot, false)
+			        + " -Tp " + GetHostPathQ(hdr_path) + " -Fp" + GetHostPathQ(cppfile)
+			        + " -Yc" + pkg[0],
+			        slot, GetHostPath(pchfile), 1))
+				error = true;
+			if(!Wait(slot))
+				error = true;
+			PutVerbose("precompiled header " + pchfile + " compiled in " + GetPrintTime(time));
+			if(error) {
+				IdeConsoleEndGroup();
+				return false;
+			}
+			DeleteFile(pchfile);
+			pch << " -Yu" << GetHostPathQ(GetFileTitle(hdr_path))
+			    << " -Fp" << GetHostPathQ(pchfile);
+		}
+	}
+
 	for(i = 0; i < pkg.GetCount(); i++) {
 		if(!IdeIsBuilding())
 			return false;
@@ -274,8 +306,10 @@ bool MscBuilder::BuildPackage(const String& package, Vector<String>& linkfile, S
 		if(b.build) {
 			PutConsole("BLITZ:" + b.info);
 			int slot = AllocSlot();
-			if(slot < 0 || ! Run(Join(cc, cpp_options) + PdbPch(package, slot, false)
-			+ " -Tp " + GetHostPathQ(b.path) + " -Fo" + GetHostPathQ(b.object), slot, GetHostPath(b.object), b.count))
+			if(slot < 0 ||
+			   !Run(Join(cc, cpp_options) + PdbPch(package, slot, false)
+			        + " -Tp " + GetHostPathQ(b.path) + " -Fo" + GetHostPathQ(b.object),
+			        slot, GetHostPath(b.object), b.count))
 				error = true;
 		}
 	}
@@ -340,7 +374,7 @@ bool MscBuilder::BuildPackage(const String& package, Vector<String>& linkfile, S
 				int slot = AllocSlot();
 				if(slot < 0 || !Run(c + PdbPch(package, slot, !sContainsPchOptions(cc) && !sContainsPchOptions(soptions[i]))
 				                    + " " + soptions[i] + (ext == ".c" ? Join(" -Tc", c_options) : Join(" -Tp", cpp_options)) + ' '
-				                    + GetHostPathQ(fn) + " -Fo" + GetHostPathQ(objfile), slot, GetHostPath(objfile), 1))
+				                    + GetHostPathQ(fn) + " -Fo" + GetHostPathQ(objfile) + pch, slot, GetHostPath(objfile), 1))
 					execerr = true;
 			}
 			if(execerr)
diff --git a/uppsrc/ide/Core/Core.cpp b/uppsrc/ide/Core/Core.cpp
index a84e56e68..5540c31c8 100644
--- a/uppsrc/ide/Core/Core.cpp
+++ b/uppsrc/ide/Core/Core.cpp
@@ -188,6 +188,11 @@ bool IdeConsoleWait()
 	return the_ide && the_ide->IdeConsoleWait();
 }
 
+bool IdeConsoleWait(int slot)
+{
+	return the_ide && the_ide->IdeConsoleWait(slot);
+}
+
 void IdeGotoCodeRef(String s)
 {
 	if(the_ide) the_ide->IdeGotoCodeRef(s);
diff --git a/uppsrc/ide/Core/Core.h b/uppsrc/ide/Core/Core.h
index 44da24a74..4ae839ffa 100644
--- a/uppsrc/ide/Core/Core.h
+++ b/uppsrc/ide/Core/Core.h
@@ -55,6 +55,7 @@ public:
 	virtual void             IdeConsoleBeginGroup(String group) = 0;
 	virtual void             IdeConsoleEndGroup() = 0;
 	virtual bool             IdeConsoleWait() = 0;
+	virtual bool             IdeConsoleWait(int slot) = 0;
 
 	virtual bool      IdeIsDebug() const = 0;
 	virtual void      IdeEndDebug() = 0;
@@ -109,6 +110,7 @@ void             IdeConsoleFlush();
 void             IdeConsoleBeginGroup(String group);
 void             IdeConsoleEndGroup();
 bool             IdeConsoleWait();
+bool             IdeConsoleWait(int slot);
 void             IdeGotoCodeRef(String s);
 
 String GetDefaultMethod();
@@ -391,6 +393,7 @@ struct Builder {
 	String           mainpackage;
 	bool             doall;
 	bool             main_conf;
+	bool             allow_pch;
 
 	virtual bool BuildPackage(const String& package, Vector<String>& linkfile, String& linkoptions,
 		const Vector<String>& all_uses, const Vector<String>& all_libraries, int optimize)
diff --git a/uppsrc/ide/Core/Hdepend.cpp b/uppsrc/ide/Core/Hdepend.cpp
index fdd2d126b..ef12c30b3 100644
--- a/uppsrc/ide/Core/Hdepend.cpp
+++ b/uppsrc/ide/Core/Hdepend.cpp
@@ -415,8 +415,6 @@ bool Hdepend::BlitzApproved(const String& path)
 		return false;
 	if(info.guarded)
 		return true;
-	if(info.guarded)
-		return true;
 	for(int i = 0; i < info.depend.GetCount(); i++)
 		if(!info.bydefine[i] && !map[info.depend[i]].CanBlitz()) {
 			PutVerbose(String().Cat() << map.GetKey(info.depend[i])
diff --git a/uppsrc/ide/Core/Host.cpp b/uppsrc/ide/Core/Host.cpp
index fc0d7a373..e9b137889 100644
--- a/uppsrc/ide/Core/Host.cpp
+++ b/uppsrc/ide/Core/Host.cpp
@@ -141,6 +141,11 @@ bool LocalHost::Wait()
 	return IdeConsoleWait();
 }
 
+bool LocalHost::Wait(int slot)
+{
+	return IdeConsoleWait(slot);
+}
+
 One<AProcess> LocalHost::StartProcess(const char *cmdline)
 {
 	try {
diff --git a/uppsrc/ide/Core/Host.h b/uppsrc/ide/Core/Host.h
index 425b74d64..4a685c3ae 100644
--- a/uppsrc/ide/Core/Host.h
+++ b/uppsrc/ide/Core/Host.h
@@ -24,6 +24,7 @@ struct Host {
 	virtual bool               Run(const char *cmdline, int slot, String key, int blitz_count) = 0;
 	virtual bool               Run(const char *cmdline, Stream& out, int slot, String key, int blitz_count) = 0;
 	virtual bool               Wait() = 0;
+	virtual bool               Wait(int slot) = 0;
 	virtual One<AProcess>      StartProcess(const char *cmdline) = 0;
 	virtual void               Launch(const char *cmdline, bool console = false) = 0;
 	virtual void               AddFlags(Index<String>& cfg) = 0;
@@ -56,6 +57,7 @@ struct LocalHost : Host {
 	virtual bool               Run(const char *cmdline, int slot, String key, int blitz_count);
 	virtual bool               Run(const char *cmdline, Stream& out, int slot, String key, int blitz_count);
 	virtual bool               Wait();
+	virtual bool               Wait(int slot);
 	virtual One<AProcess>      StartProcess(const char *cmdline);
 	virtual void               Launch(const char *cmdline, bool console);
 	virtual void               AddFlags(Index<String>& cfg);
diff --git a/uppsrc/ide/Methods.cpp b/uppsrc/ide/Methods.cpp
index 1bc2e0797..f36d2731f 100644
--- a/uppsrc/ide/Methods.cpp
+++ b/uppsrc/ide/Methods.cpp
@@ -145,6 +145,7 @@ struct BuildMethods : public WithBuildMethodsLayout<TopWindow>
 	TextOption release_blitz;
 	TextSwitch release_linkmode;
 	TextOption linkmode_lock;
+	TextOption allow_pch;
 	DirTable   path;
 	DirTable   include;
 	DirTable   lib;
@@ -219,6 +220,10 @@ BuildMethods::BuildMethods()
 #endif
 	method.AddCtrl("SCRIPT", scriptfile);
 	method.AddCtrl("LINKMODE_LOCK", linkmode_lock);
+	
+	allow_pch.SetLabel("Allow precompiled headers");
+	method.AddCtrl("ALLOW_PRECOMPILED_HEADERS", allow_pch);
+	
 	open_script.Attach(scriptfile);
 	open_script.Type("Build scripts (*.bsc)", "*.bsc")
 		.AllFilesType();
diff --git a/uppsrc/ide/ide.h b/uppsrc/ide/ide.h
index 06fae9d53..36473f8e0 100644
--- a/uppsrc/ide/ide.h
+++ b/uppsrc/ide/ide.h
@@ -572,6 +572,7 @@ public:
 	virtual   void             IdeConsoleBeginGroup(String group);
 	virtual   void             IdeConsoleEndGroup();
 	virtual   bool             IdeConsoleWait();
+	virtual   bool             IdeConsoleWait(int slot);
 
 	virtual   bool      IdeIsDebug() const;
 	virtual   void      IdeEndDebug();
diff --git a/uppsrc/ide/ide.lay b/uppsrc/ide/ide.lay
index c86a5f29c..2f03f2bd2 100644
--- a/uppsrc/ide/ide.lay
+++ b/uppsrc/ide/ide.lay
@@ -181,36 +181,36 @@ LAYOUT(BuildMethodsLayout, 788, 560)
 	ITEM(EditString, compiler, RightPosZ(264, 116).TopPosZ(4, 19))
 	ITEM(Label, dv___5, SetLabel(t_("&External debugger:")).RightPosZ(152, 100).TopPosZ(4, 19))
 	ITEM(EditString, debugger, RightPosZ(8, 140).TopPosZ(4, 20))
-	ITEM(Label, dv___7, SetLabel(t_("Common options")).LeftPosZ(160, 108).TopPosZ(36, 19))
-	ITEM(EditString, common_options, HSizePosZ(276, 8).TopPosZ(36, 19))
-	ITEM(Label, dv___9, SetLabel(t_("Common C++ options")).LeftPosZ(160, 116).TopPosZ(56, 19))
-	ITEM(EditString, common_cpp_options, HSizePosZ(276, 8).TopPosZ(56, 19))
-	ITEM(Label, dv___11, SetLabel(t_("Common C options")).LeftPosZ(160, 108).TopPosZ(76, 19))
-	ITEM(EditString, common_c_options, HSizePosZ(276, 8).TopPosZ(76, 19))
-	ITEM(Label, dv___13, SetLabel(t_("Common fixed flags")).LeftPosZ(160, 108).TopPosZ(96, 19))
-	ITEM(EditString, common_flags, HSizePosZ(276, 8).TopPosZ(96, 19))
-	ITEM(LabelBox, dv___15, SetLabel(t_("Debug mode defaults")).HSizePosZ(160, 8).TopPosZ(124, 44))
-	ITEM(Label, dv___16, SetLabel(t_("Default debug info level:")).LeftPosZ(168, 132).TopPosZ(140, 19))
-	ITEM(DropList, debug_info, HSizePosZ(304, 368).TopPosZ(140, 19))
-	UNTYPED(debug_blitz, SwitchImage(false).SetLabel(t_("Use BLIT&Z")).HSizePosZ(428, 272).TopPosZ(140, 15))
-	UNTYPED(debug_linkmode, SetLabel(t_("All static\nShared libs\nAll shared")).HSizePosZ(540, -4).TopPosZ(140, 15))
-	ITEM(Label, dv___20, SetLabel(t_("&Debug options:")).LeftPosZ(160, 100).TopPosZ(172, 19))
-	ITEM(EditString, debug_options, HSizePosZ(276, 8).TopPosZ(172, 19))
-	ITEM(Label, dv___22, SetLabel(t_("Debug fixed flags:")).LeftPosZ(160, 100).TopPosZ(192, 19))
-	ITEM(EditString, debug_flags, HSizePosZ(276, 8).TopPosZ(192, 19))
-	ITEM(Label, dv___24, SetLabel(t_("Debug link options:")).LeftPosZ(160, 100).TopPosZ(212, 19))
-	ITEM(EditString, debug_link, HSizePosZ(276, 8).TopPosZ(212, 19))
-	UNTYPED(release_linkmode, SetLabel(t_("All static\nShared libs\nAll shared")).RightPosZ(-8, 256).TopPosZ(256, 15))
-	ITEM(LabelBox, dv___27, SetLabel(t_("Release mode defaults")).RightPosZ(8, 620).TopPosZ(240, 40))
-	UNTYPED(release_blitz, SwitchImage(false).SetLabel(t_("&Use BLITZ")).RightPosZ(364, 256).TopPosZ(256, 15))
-	ITEM(Label, dv___29, SetLabel(t_("Optimize for speed:")).RightPosZ(520, 108).TopPosZ(284, 19))
-	ITEM(EditString, speed_options, RightPosZ(8, 504).TopPosZ(284, 19))
-	ITEM(Label, dv___31, SetLabel(t_("Optimize for size:")).RightPosZ(520, 108).TopPosZ(304, 19))
-	ITEM(EditString, size_options, RightPosZ(8, 504).TopPosZ(304, 19))
-	ITEM(Label, dv___33, SetLabel(t_("Release fixed flags:")).RightPosZ(520, 108).TopPosZ(324, 19))
-	ITEM(EditString, release_flags, RightPosZ(8, 504).TopPosZ(324, 19))
-	ITEM(Label, dv___35, SetLabel(t_("Release link options:")).RightPosZ(520, 108).TopPosZ(344, 19))
-	ITEM(EditString, release_link, RightPosZ(8, 504).TopPosZ(344, 19))
+	ITEM(Label, dv___7, SetLabel(t_("Common options")).LeftPosZ(160, 108).TopPosZ(28, 19))
+	ITEM(EditString, common_options, HSizePosZ(276, 8).TopPosZ(28, 19))
+	ITEM(Label, dv___9, SetLabel(t_("Common C++ options")).LeftPosZ(160, 116).TopPosZ(48, 19))
+	ITEM(EditString, common_cpp_options, HSizePosZ(276, 8).TopPosZ(48, 19))
+	ITEM(Label, dv___11, SetLabel(t_("Common C options")).LeftPosZ(160, 108).TopPosZ(68, 19))
+	ITEM(EditString, common_c_options, HSizePosZ(276, 8).TopPosZ(68, 19))
+	ITEM(Label, dv___13, SetLabel(t_("Common fixed flags")).LeftPosZ(160, 108).TopPosZ(88, 19))
+	ITEM(EditString, common_flags, HSizePosZ(276, 8).TopPosZ(88, 19))
+	ITEM(LabelBox, dv___15, SetLabel(t_("Debug mode defaults")).HSizePosZ(160, 8).TopPosZ(116, 44))
+	ITEM(Label, dv___16, SetLabel(t_("Default debug info level:")).LeftPosZ(168, 132).TopPosZ(132, 19))
+	ITEM(DropList, debug_info, HSizePosZ(304, 368).TopPosZ(132, 19))
+	UNTYPED(debug_blitz, SwitchImage(false).SetLabel(t_("Use BLIT&Z")).HSizePosZ(428, 272).TopPosZ(132, 15))
+	UNTYPED(debug_linkmode, SetLabel(t_("All static\nShared libs\nAll shared")).HSizePosZ(540, -4).TopPosZ(132, 15))
+	ITEM(Label, dv___20, SetLabel(t_("&Debug options:")).LeftPosZ(160, 100).TopPosZ(164, 19))
+	ITEM(EditString, debug_options, HSizePosZ(276, 8).TopPosZ(164, 19))
+	ITEM(Label, dv___22, SetLabel(t_("Debug fixed flags:")).LeftPosZ(160, 100).TopPosZ(184, 19))
+	ITEM(EditString, debug_flags, HSizePosZ(276, 8).TopPosZ(184, 19))
+	ITEM(Label, dv___24, SetLabel(t_("Debug link options:")).LeftPosZ(160, 100).TopPosZ(204, 19))
+	ITEM(EditString, debug_link, HSizePosZ(276, 8).TopPosZ(204, 19))
+	UNTYPED(release_linkmode, SetLabel(t_("All static\nShared libs\nAll shared")).RightPosZ(-8, 256).TopPosZ(248, 15))
+	ITEM(LabelBox, dv___27, SetLabel(t_("Release mode defaults")).RightPosZ(8, 620).TopPosZ(232, 40))
+	UNTYPED(release_blitz, SwitchImage(false).SetLabel(t_("&Use BLITZ")).RightPosZ(364, 256).TopPosZ(248, 15))
+	ITEM(Label, dv___29, SetLabel(t_("Optimize for speed:")).RightPosZ(520, 108).TopPosZ(276, 19))
+	ITEM(EditString, speed_options, RightPosZ(8, 504).TopPosZ(276, 19))
+	ITEM(Label, dv___31, SetLabel(t_("Optimize for size:")).RightPosZ(520, 108).TopPosZ(296, 19))
+	ITEM(EditString, size_options, RightPosZ(8, 504).TopPosZ(296, 19))
+	ITEM(Label, dv___33, SetLabel(t_("Release fixed flags:")).RightPosZ(520, 108).TopPosZ(316, 19))
+	ITEM(EditString, release_flags, RightPosZ(8, 504).TopPosZ(316, 19))
+	ITEM(Label, dv___35, SetLabel(t_("Release link options:")).RightPosZ(520, 108).TopPosZ(336, 19))
+	ITEM(EditString, release_link, RightPosZ(8, 504).TopPosZ(336, 19))
 	UNTYPED(linkmode_lock, LeftPosZ(4, 148).BottomPosZ(156, 20))
 	ITEM(Label, dv___38, SetLabel(t_("Script file:")).LeftPosZ(4, 68).BottomPosZ(133, 19))
 	ITEM(EditField, scriptfile, LeftPosZ(4, 152).BottomPosZ(113, 19))
@@ -219,6 +219,7 @@ LAYOUT(BuildMethodsLayout, 788, 560)
 	ITEM(TabCtrl, paths, HSizePosZ(160, 8).VSizePosZ(376, 40))
 	ITEM(Button, ok, SetLabel(t_("OK")).RightPosZ(76, 64).BottomPosZ(10, 22))
 	ITEM(Button, cancel, SetLabel(t_("Cancel")).RightPosZ(8, 64).BottomPosZ(10, 22))
+	UNTYPED(allow_pch, LeftPosZ(160, 212).TopPosZ(356, 16))
 END_LAYOUT
 
 LAYOUT(ModePaneLayout, 288, 460)
diff --git a/uppsrc/ide/idewin.cpp b/uppsrc/ide/idewin.cpp
index caa164286..1813308c6 100644
--- a/uppsrc/ide/idewin.cpp
+++ b/uppsrc/ide/idewin.cpp
@@ -156,6 +156,12 @@ bool Ide::IdeConsoleWait()
 	return console.Wait();
 }
 
+bool Ide::IdeConsoleWait(int slot)
+{
+	console.Wait(slot);
+	return true;
+}
+
 void Ide::IdeSetRight(Ctrl& ctrl)
 {
 	right.Add(ctrl.SizePos());