diff --git a/src/Makefile.am b/src/Makefile.am
index 120bff9881..df17ab4afc 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -316,7 +316,7 @@ endif
 
 #########################  Qt stuff  ##############################
 
-MOCHEADER = Compare.h
+MOCHEADER = Compare.h PreviewLoader.h
 
 if INSTALL_WINDOWS
 
@@ -330,6 +330,9 @@ MOCEDFILES = $(MOCHEADER:%.h=moc_%.cpp)
 BUILT_SOURCES += $(MOCEDFILES)
 CLEANFILES += $(MOCEDFILES)
 
+moc_PreviewLoader.cpp: graphics/PreviewLoader.h
+	$(MOC4) $(MOCFLAG) -o $@ $<
+
 moc_%.cpp: %.h
 	$(MOC4) $(MOCFLAG) -o $@ $<
 
diff --git a/src/graphics/CMakeLists.txt b/src/graphics/CMakeLists.txt
index d0708bd309..2b38d0c98e 100644
--- a/src/graphics/CMakeLists.txt
+++ b/src/graphics/CMakeLists.txt
@@ -13,6 +13,8 @@ lyx_add_msvc_pch(graphics)
 
 
 include_directories(${TOP_SRC_DIR}/src/graphics)
+lyx_automoc(${TOP_SRC_DIR}/src/graphics/PreviewLoader.cpp)
+include_directories(${CMAKE_CURRENT_BINARY_DIR} ${QT_INCLUDES})
 
 if(NOT LYX_MERGE_FILES)
 	add_library(graphics ${library_type} ${graphics_sources} ${graphics_headers})
@@ -21,6 +23,7 @@ else()
 	add_library(graphics ${library_type} ${_allinone_files})
 endif()
 set_target_properties(graphics PROPERTIES FOLDER "applications/LyX")
+qt_use_modules(graphics Core)
 
 lyx_add_gcc_pch(graphics)
 
diff --git a/src/graphics/PreviewLoader.cpp b/src/graphics/PreviewLoader.cpp
index 7d2f81cce1..1a8b7fadd6 100644
--- a/src/graphics/PreviewLoader.cpp
+++ b/src/graphics/PreviewLoader.cpp
@@ -44,6 +44,8 @@
 #include <fstream>
 #include <iomanip>
 
+#include <QTimer>
+
 using namespace std;
 using namespace lyx::support;
 
@@ -207,6 +209,8 @@ public:
 	/// \p wait whether to wait for the process to complete or, instead,
 	/// to do it in the background.
 	void startLoading(bool wait = false);
+	///
+	void refreshPreviews();
 
 	/// Emit this signal when an image is ready for display.
 	boost::signal<void(PreviewImage const &)> imageReady;
@@ -247,6 +251,8 @@ private:
 	Buffer const & buffer_;
 	///
 	mutable int font_scaling_factor_;
+	///
+	QTimer * delay_refresh_;
 
 	/// We don't own this
 	static lyx::Converter const * pconverter_;
@@ -301,6 +307,12 @@ void PreviewLoader::startLoading(bool wait) const
 }
 
 
+void PreviewLoader::refreshPreviews()
+{
+	pimpl_->refreshPreviews();
+}
+
+
 boost::signals::connection PreviewLoader::connect(slot_type const & slot) const
 {
 	return pimpl_->imageReady.connect(slot);
@@ -396,11 +408,18 @@ PreviewLoader::Impl::Impl(PreviewLoader & p, Buffer const & b)
 		: int(0.01 * lyxrc.dpi * lyxrc.zoom * lyxrc.preview_scale_factor);
 	if (!pconverter_)
 		pconverter_ = setConverter("lyxpreview");
+
+	delay_refresh_ = new QTimer(&parent_);
+	delay_refresh_->setSingleShot(true);
+	QObject::connect(delay_refresh_, SIGNAL(timeout()),
+	                 &parent_, SLOT(refreshPreviews()));
 }
 
 
 PreviewLoader::Impl::~Impl()
 {
+	delete delay_refresh_;
+
 	InProgressProcesses::iterator ipit  = in_progress_.begin();
 	InProgressProcesses::iterator ipend = in_progress_.end();
 
@@ -416,18 +435,32 @@ PreviewLoader::Impl::preview(string const & latex_snippet) const
 		? int(75.0 * buffer_.params().html_math_img_scale)
 		: int(0.01 * lyxrc.dpi * lyxrc.zoom * lyxrc.preview_scale_factor);
 	if (font_scaling_factor_ != fs) {
-		font_scaling_factor_ = fs;
-		Cache::const_iterator cit = cache_.begin();
-		Cache::const_iterator cend = cache_.end();
-		while (cit != cend)
-			parent_.remove((cit++)->first);
-		buffer_.updatePreviews();
+		// Schedule refresh of all previews on zoom changes.
+		// The previews are regenerated only after the zoom factor
+		// has not been changed for about 1 second.
+		delay_refresh_->start(1000);
 	}
+	// Don't try to access the cache until we are done.
+	if (delay_refresh_->isActive())
+		return 0;
 	Cache::const_iterator it = cache_.find(latex_snippet);
 	return (it == cache_.end()) ? 0 : it->second.get();
 }
 
 
+void PreviewLoader::Impl::refreshPreviews()
+{
+	font_scaling_factor_ = buffer_.isExporting()
+		? int(75.0 * buffer_.params().html_math_img_scale)
+		: int(0.01 * lyxrc.dpi * lyxrc.zoom * lyxrc.preview_scale_factor);
+	Cache::const_iterator cit = cache_.begin();
+	Cache::const_iterator cend = cache_.end();
+	while (cit != cend)
+		parent_.remove((cit++)->first);
+	buffer_.updatePreviews();
+}
+
+
 namespace {
 
 class FindSnippet {
@@ -782,3 +815,5 @@ void PreviewLoader::Impl::dumpData(odocstream & os,
 
 } // namespace graphics
 } // namespace lyx
+
+#include "moc_PreviewLoader.cpp"
diff --git a/src/graphics/PreviewLoader.h b/src/graphics/PreviewLoader.h
index 6910984c9e..7f2c71e33f 100644
--- a/src/graphics/PreviewLoader.h
+++ b/src/graphics/PreviewLoader.h
@@ -20,6 +20,8 @@
 
 #include <boost/signal.hpp>
 
+#include <QObject>
+
 #include "ColorCode.h"
 
 namespace lyx {
@@ -30,7 +32,8 @@ namespace graphics {
 
 class PreviewImage;
 
-class PreviewLoader {
+class PreviewLoader : public QObject {
+	Q_OBJECT
 public:
 	/** We need buffer because we require the preamble to the
 	 *  LaTeX file.
@@ -91,6 +94,10 @@ public:
 	/// The foreground color used
 	static ColorCode foregroundColor() { return Color_preview; }
 
+public Q_SLOTS:
+	///
+	void refreshPreviews();
+
 private:
 	/// noncopyable
 	PreviewLoader(PreviewLoader const &);
diff --git a/src/mathed/CMakeLists.txt b/src/mathed/CMakeLists.txt
index 04c1a51939..8d354f6a13 100644
--- a/src/mathed/CMakeLists.txt
+++ b/src/mathed/CMakeLists.txt
@@ -14,7 +14,7 @@ list(REMOVE_ITEM mathed_sources
 
 lyx_add_msvc_pch(mathed)
 
-include_directories(${TOP_SRC_DIR}/src/mathed)
+include_directories(${TOP_SRC_DIR}/src/mathed ${QT_INCLUDES})
 
 if(NOT LYX_MERGE_FILES)
 	add_library(mathed ${library_type} ${mathed_sources} ${mathed_headers})
@@ -23,6 +23,7 @@ else()
 	add_library(mathed ${library_type} ${_allinone_files})
 endif()
 set_target_properties(mathed PROPERTIES FOLDER "applications/LyX")
+qt_use_modules(mathed Core)
 
 lyx_add_gcc_pch(mathed)