skip recalculating radar values and last beat when loading from cache. loading songs from the cache is now 5x faster.

fyi: it took 1:40 minutes to load my library, now it's only 20 seconds.

src/Song.cpp

@@ -236,9 +236,7 @@ bool Song::LoadFromSongDir( RString sDir )
 	{
 //		LOG->Trace( "Loading '%s' from cache file '%s'.", m_sSongDir.c_str(), GetCacheFilePath().c_str() );
 		bool bLoadedFromSSC = SSCLoader::LoadFromSSCFile( sCacheFilePath, *this, true );
-		if( bLoadedFromSSC )
-			SSCLoader::TidyUpData( *this, true );
-		else
+		if( !bLoadedFromSSC )
 		{
 			// load from .sm
 			SMLoader::LoadFromSMFile( sCacheFilePath, *this, true );
@@ -390,7 +388,7 @@ void FixupPath( RString &path, const RString &sSongPath )
 }
 
 // Songs in BlacklistImages will never be autodetected as song images.
-void Song::TidyUpData()
+void Song::TidyUpData( bool bFromCache )
 {
 	// We need to do this before calling any of HasMusic, HasHasCDTitle, etc.
 	ASSERT_M( m_sSongDir.Left(3) != "../", m_sSongDir ); // meaningless
@@ -481,7 +479,7 @@ void Song::TidyUpData()
 
 	/* Generate these before we autogen notes, so the new notes can inherit
 	 * their source's values. */
-	ReCalculateRadarValuesAndLastBeat();
+	ReCalculateRadarValuesAndLastBeat( bFromCache );
 
 	Trim( m_sMainTitle );
 	Trim( m_sSubTitle );
@@ -791,8 +789,16 @@ void Song::TranslateTitles()
 	title.SaveToStrings( m_sMainTitle, m_sSubTitle, m_sArtist, m_sMainTitleTranslit, m_sSubTitleTranslit, m_sArtistTranslit );
 }
 
-void Song::ReCalculateRadarValuesAndLastBeat()
+void Song::ReCalculateRadarValuesAndLastBeat( bool bFromCache )
 {
+	if( bFromCache && m_fFirstBeat >= 0 && m_fLastBeat > 0 )
+	{
+		// this is loaded from cache, then we just have to calculate the radar values.
+		for( unsigned i=0; i<m_vpSteps.size(); i++ )
+			m_vpSteps[i]->CalculateRadarValues( m_fMusicLengthSeconds );
+		return;
+	}
+
 	float fFirstBeat = FLT_MAX; // inf
 	float fLastBeat = m_fSpecifiedLastBeat; // Make sure we're at least as long as the specified amount.