Don't compute the compressed string or the hash unless it is required.

stepmania/src/Steps.cpp

@@ -45,6 +45,22 @@ Steps::~Steps()
 {
 }
 
+unsigned Steps::GetHash() const
+{
+	if( parent )
+		return parent->GetHash();
+	if( m_uHash )
+		return m_uHash;
+	if( m_sNoteDataCompressed.empty() )
+	{
+		if( !m_bNoteDataIsFilled )
+			return 0; // No data, no hash.
+		NoteDataUtil::GetSMNoteDataString( *m_pNoteData, m_sNoteDataCompressed );
+	}
+	m_uHash = GetHashForString( m_sNoteDataCompressed );
+	return m_uHash;
+}		
+
 void Steps::SetNoteData( const NoteData& noteDataNew )
 {
 	ASSERT( noteDataNew.GetNumTracks() == GameManager::StepsTypeToNumTracks(m_StepsType) );
@@ -61,8 +77,8 @@ void Steps::SetNoteData( const NoteData& noteDataNew )
 	*m_pNoteData = noteDataNew;
 	m_bNoteDataIsFilled = true;
 	
-	NoteDataUtil::GetSMNoteDataString( *m_pNoteData, m_sNoteDataCompressed );
+	m_sNoteDataCompressed = EMPTY_STRING;
-	m_uHash = GetHashForString( m_sNoteDataCompressed );
+	m_uHash = 0;
 	m_sFilename = EMPTY_STRING; // We can no longer read from the file because it has changed in memory.
 }
 
@@ -87,7 +103,7 @@ void Steps::SetSMNoteData( const RString &notes_comp_ )
 	m_bNoteDataIsFilled = false;
 
 	m_sNoteDataCompressed = notes_comp_;
-	m_uHash = GetHashForString( m_sNoteDataCompressed );
+	m_uHash = 0;
 	m_sFilename = EMPTY_STRING; // We can no longer read from the file because it has changed in memory.
 }
 

stepmania/src/Steps.h

@@ -36,7 +36,6 @@ public:
 	bool IsAPlayerEdit() const			{ return IsAnEdit() && GetLoadedFromProfileSlot() < ProfileSlot_Machine; }
 	bool WasLoadedFromProfile() const		{ return m_LoadedFromProfile != ProfileSlot_INVALID; }
 	ProfileSlot GetLoadedFromProfileSlot() const	{ return m_LoadedFromProfile; }
-	unsigned GetHash() const			{ return Real()->m_uHash; }
 	RString GetDescription() const			{ return Real()->m_sDescription; }
 	Difficulty GetDifficulty() const		{ return Real()->m_Difficulty; }
 	int GetMeter() const				{ return Real()->m_iMeter; }
@@ -56,6 +55,7 @@ public:
 	void SetCachedRadarValues( const RadarValues v[NUM_PLAYERS] );
 	float PredictMeter() const;
 	
+	unsigned GetHash() const;
 	void GetNoteData( NoteData& noteDataOut ) const;
 	void SetNoteData( const NoteData& noteDataNew );
 	void SetSMNoteData( const RString &notes_comp );
@@ -87,7 +87,7 @@ private:
 	ProfileSlot			m_LoadedFromProfile;	// ProfileSlot_INVALID if wasn't loaded from a profile
 
 	/* These values are pulled from the autogen source first, if there is one. */
-	unsigned			m_uHash;		// only used if m_Difficulty == DIFFICULTY_EDIT
+	mutable unsigned		m_uHash;		// only used if m_Difficulty == DIFFICULTY_EDIT
 	RString				m_sDescription;		// Step author, edit name, or something meaningful
 	Difficulty			m_Difficulty;		// difficulty classification
 	int				m_iMeter;		// difficulty rating from MIN_METER to MAX_METER