diff --git a/indra/newview/fsappviewerwin32.cpp b/indra/newview/fsappviewerwin32.cpp
new file mode 100644
index 0000000000..3daaf17f0e
--- /dev/null
+++ b/indra/newview/fsappviewerwin32.cpp
@@ -0,0 +1,110 @@
+// <FS:ND> Thread to purge old texture cache in the background.
+// The cache dir will be search for directories named *.old_texturecache, then each of this directories
+// will be deleted.
+// The thread will be started each time the viewer starts, just in case there is directories so huge,
+// the user quit the viewer before the old cache was fully cleared.
+
+void deleteFilesInDirectory( std::wstring aDir )
+{
+	if( aDir == L"." || aDir == L".." || aDir.empty() )
+		return;
+
+	if( aDir[ aDir.size() -1 ] != '\\' || aDir[ aDir.size() -1 ] != '/' )
+		aDir += L"\\";
+
+	WIN32_FIND_DATA oFindData;
+	HANDLE hFindHandle = ::FindFirstFile( (aDir + L"*.*").c_str(), &oFindData );
+
+	if( INVALID_HANDLE_VALUE == hFindHandle )
+		return;
+
+	do
+	{
+		if( ! (oFindData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY ) )
+		{
+			std::wstring strFile = aDir + oFindData.cFileName;
+			if( oFindData.dwFileAttributes & FILE_ATTRIBUTE_READONLY )
+				::SetFileAttributes( strFile.c_str(), FILE_ATTRIBUTE_NORMAL );
+
+			::DeleteFile( ( aDir + oFindData.cFileName ).c_str() );
+		}
+	} while( ::FindNextFile( hFindHandle, &oFindData ) );
+
+	::FindClose( hFindHandle );
+}
+
+void deleteCacheDirectory( std::wstring aDir )
+{
+	if( aDir == L"." || aDir == L".." || aDir.empty() )
+		return;
+
+	if( aDir[ aDir.size() -1 ] != '\\' || aDir[ aDir.size() -1 ] != '/' )
+		aDir += L"\\";
+
+	wchar_t aCacheDirs[] = L"0123456789abcdef";
+
+	for( int i = 0; i < _countof( aCacheDirs ); ++i )
+	{
+		deleteFilesInDirectory( aDir + aCacheDirs[i] );
+		::RemoveDirectory( (aDir + aCacheDirs[i]).c_str() );
+	}
+
+	deleteFilesInDirectory( aDir );
+	::RemoveDirectory( aDir.c_str() );
+}
+
+DWORD WINAPI purgeThread( LPVOID lpParameter )
+{
+	wchar_t *pDir = reinterpret_cast< wchar_t* >( lpParameter );
+	if( !pDir )
+		return 0;
+
+	std::wstring strPath = pDir;
+	free( pDir );
+
+	if( strPath.empty() )
+		return 0;
+
+	if( strPath[ strPath.size() -1 ] != '\\' || strPath[ strPath.size() -1 ] != '/' )
+		strPath += L"\\";
+
+	WIN32_FIND_DATA oFindData;
+	HANDLE hFindHandle = ::FindFirstFile( ( strPath + L"*.old_texturecache" ).c_str(), &oFindData );
+
+	std::vector< std::wstring > vctDirs;
+
+	if( INVALID_HANDLE_VALUE == hFindHandle )
+		return 0;
+
+	do
+	{
+		if( oFindData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY )
+			vctDirs.push_back( strPath + oFindData.cFileName );
+	} while( ::FindNextFile( hFindHandle, &oFindData ) );
+
+	::FindClose( hFindHandle );
+
+	for( auto dir : vctDirs )
+		deleteCacheDirectory( dir );
+
+	return 0;
+}
+
+void LLAppViewerWin32::startCachePurge()
+{
+	if( isSecondInstance() )
+		return;
+
+    std::wstring strCacheDir = wstringize( gDirUtilp->getExpandedFilename( LL_PATH_CACHE, "" ) );
+
+	HANDLE hThread = CreateThread( nullptr, 0, purgeThread, _wcsdup( strCacheDir.c_str() ), 0, nullptr );
+
+	if( !hThread )
+	{
+        LL_WARNS("CachePurge") << "CreateThread failed: "  << GetLastError() << LL_ENDL;
+    }
+	else
+		SetThreadPriority( hThread, THREAD_MODE_BACKGROUND_BEGIN );
+}
+
+// </FS:ND>
diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp
index 3a9e2a8c48..0932aa0f89 100755
--- a/indra/newview/llappviewer.cpp
+++ b/indra/newview/llappviewer.cpp
@@ -5132,6 +5132,10 @@ bool LLAppViewer::initCache()
 	}
 	// </FS:Ansariel>
 
+	// <FS:ND> For Windows, purging the cache can take an extraordinary amount of time. Rename the cache dir and purge it using another thread.
+	startCachePurge();
+	// </FS:ND>
+
 	LLSplashScreen::update(LLTrans::getString("StartupInitializingTextureCache"));
 	
 	// Init the texture cache
diff --git a/indra/newview/llappviewer.h b/indra/newview/llappviewer.h
index dca4fc42b4..1438153873 100755
--- a/indra/newview/llappviewer.h
+++ b/indra/newview/llappviewer.h
@@ -350,6 +350,11 @@ public:
 	void setSaveSettingsOnExit(bool state) {mSaveSettingsOnExit = state; };
 	bool mSaveSettingsOnExit;
 	// </FS:Zi>
+
+// <FS:ND> For Windows, purging the cache can take an extraordinary amount of time. Rename the cache dir and purge it using another thread.
+private:
+	virtual void startCachePurge() {}
+// </FS:ND>
 };
 
 // consts from viewer.h
diff --git a/indra/newview/llappviewerwin32.cpp b/indra/newview/llappviewerwin32.cpp
index 4c8bf190dc..0e0b5855e5 100644
--- a/indra/newview/llappviewerwin32.cpp
+++ b/indra/newview/llappviewerwin32.cpp
@@ -937,3 +937,5 @@ std::string LLAppViewerWin32::generateSerialNumber()
 	}
 	return serial_md5;
 }
+
+#include "fsappviewerwin32.cpp"
diff --git a/indra/newview/llappviewerwin32.h b/indra/newview/llappviewerwin32.h
index 59d1ddaa3d..afa8b014a6 100644
--- a/indra/newview/llappviewerwin32.h
+++ b/indra/newview/llappviewerwin32.h
@@ -63,6 +63,11 @@ private:
 
 	std::string mCmdLine;
 	bool mIsConsoleAllocated;
+
+// <FS:ND> For Windows, purging the cache can take an extraordinary amount of time. Rename the cache dir and purge it using another thread.
+	virtual void startCachePurge();
+// </FS:ND>
+
 };
 
 #endif // LL_LLAPPVIEWERWIN32_H
diff --git a/indra/newview/lltexturecache.cpp b/indra/newview/lltexturecache.cpp
index bea852ea5b..417d8c49ee 100755
--- a/indra/newview/lltexturecache.cpp
+++ b/indra/newview/lltexturecache.cpp
@@ -1542,6 +1542,25 @@ void LLTextureCache::purgeAllTextures(bool purge_directories)
 {
 	if (!mReadOnly)
 	{
+// <FS:ND> Windows can be really slow deleting a huge texture cache.
+// In case of a full purge rename the directory and then purge this using a low priority background thread. 
+#if LL_WINDOWS
+		bool bOldPurge = true;
+		if( purge_directories )
+		{
+			std::string strNewName = mCacheParentDirName + gDirUtilp->getDirDelimiter() + LLUUID::generateNewID().asString() + ".old_texturecache";
+			if( LLFile::isdir( mTexturesDirName ) )
+				bOldPurge = ( 0 != LLFile::rename( mTexturesDirName, strNewName ) );
+
+			if( bOldPurge )
+			{
+				LL_WARNS() << "Rename of " << mTexturesDirName << " to " << strNewName << " failed" << LL_ENDL;
+			}
+		}
+		if( !purge_directories || bOldPurge )
+#endif
+// </FS:ND>
+		{
 		const char* subdirs = "0123456789abcdef";
 		std::string delem = gDirUtilp->getDirDelimiter();
 		std::string mask = "*";
@@ -1565,7 +1584,8 @@ void LLTextureCache::purgeAllTextures(bool purge_directories)
 		{
 			gDirUtilp->deleteFilesInDir(mTexturesDirName, mask);
 			LLFile::rmdir(mTexturesDirName);
-		}		
+		}
+		}
 	}
 	mHeaderIDMap.clear();
 	mTexturesSizeMap.clear();