diff --git a/src/activeobject.h b/src/activeobject.h
index 48f078d3f..fe6c08514 100644
--- a/src/activeobject.h
+++ b/src/activeobject.h
@@ -64,7 +64,7 @@ public:
 		m_id(id)
 	{
 	}
-	
+
 	u16 getId()
 	{
 		return m_id;
@@ -76,8 +76,8 @@ public:
 	}
 
 	virtual ActiveObjectType getType() const = 0;
-	virtual bool getCollisionBox(aabb3f *toset) = 0;
-	virtual bool collideWithObjects() = 0;
+	virtual bool getCollisionBox(aabb3f *toset) const = 0;
+	virtual bool collideWithObjects() const = 0;
 protected:
 	u16 m_id; // 0 is invalid, "no id"
 };
diff --git a/src/clientobject.h b/src/clientobject.h
index f0bde0adc..1db5bcf24 100644
--- a/src/clientobject.h
+++ b/src/clientobject.h
@@ -47,8 +47,8 @@ public:
 	virtual void updateLightNoCheck(u8 light_at_pos){}
 	virtual v3s16 getLightPosition(){return v3s16(0,0,0);}
 	virtual aabb3f *getSelectionBox() { return NULL; }
-	virtual bool getCollisionBox(aabb3f *toset){return false;}
-	virtual bool collideWithObjects(){return false;}
+	virtual bool getCollisionBox(aabb3f *toset) const { return false; }
+	virtual bool collideWithObjects() const { return false; }
 	virtual v3f getPosition(){return v3f(0,0,0);}
 	virtual float getYaw() const {return 0;}
 	virtual scene::ISceneNode *getSceneNode(){return NULL;}
diff --git a/src/content_cao.cpp b/src/content_cao.cpp
index a4c0bf14d..5ddbd27c9 100644
--- a/src/content_cao.cpp
+++ b/src/content_cao.cpp
@@ -159,7 +159,7 @@ public:
 
 	void processMessage(const std::string &data);
 
-	bool getCollisionBox(aabb3f *toset) { return false; }
+	bool getCollisionBox(aabb3f *toset) const { return false; }
 private:
 	scene::IMeshSceneNode *m_node;
 	v3f m_position;
@@ -316,7 +316,7 @@ public:
 	std::string infoText()
 		{return m_infotext;}
 
-	bool getCollisionBox(aabb3f *toset) { return false; }
+	bool getCollisionBox(aabb3f *toset) const { return false; }
 private:
 	aabb3f m_selection_box;
 	scene::IMeshSceneNode *m_node;
@@ -587,7 +587,7 @@ GenericCAO::GenericCAO(Client *client, ClientEnvironment *env):
 	}
 }
 
-bool GenericCAO::getCollisionBox(aabb3f *toset)
+bool GenericCAO::getCollisionBox(aabb3f *toset) const
 {
 	if (m_prop.physical)
 	{
diff --git a/src/content_cao.h b/src/content_cao.h
index 96a160055..19fecdde5 100644
--- a/src/content_cao.h
+++ b/src/content_cao.h
@@ -130,7 +130,7 @@ public:
 
 	ClientActiveObject *getParent();
 
-	bool getCollisionBox(aabb3f *toset);
+	bool getCollisionBox(aabb3f *toset) const;
 
 	bool collideWithObjects();
 
diff --git a/src/content_sao.cpp b/src/content_sao.cpp
index dd8bdc592..c403a3673 100644
--- a/src/content_sao.cpp
+++ b/src/content_sao.cpp
@@ -19,11 +19,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "content_sao.h"
 #include "util/serialize.h"
-#include "util/mathconstants.h"
 #include "collision.h"
 #include "environment.h"
-#include "settings.h"
-#include "serialization.h" // For compressZlib
 #include "tool.h" // For ToolCapabilities
 #include "gamedef.h"
 #include "nodedef.h"
@@ -31,7 +28,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "server.h"
 #include "scripting_game.h"
 #include "genericobject.h"
-#include "log.h"
 
 std::map<u16, ServerActiveObject::Factory> ServerActiveObject::m_types;
 
@@ -94,13 +90,8 @@ public:
 		}
 	}
 
-	bool getCollisionBox(aabb3f *toset) {
-		return false;
-	}
-
-	bool collideWithObjects() {
-		return false;
-	}
+	bool getCollisionBox(aabb3f *toset) const { return false; }
+	bool collideWithObjects() const { return false; }
 
 private:
 	float m_timer1;
@@ -110,6 +101,28 @@ private:
 // Prototype (registers item for deserialization)
 TestSAO proto_TestSAO(NULL, v3f(0,0,0));
 
+/*
+	UnitSAO
+ */
+
+UnitSAO::UnitSAO(ServerEnvironment *env, v3f pos):
+	ServerActiveObject(env, pos),
+	m_hp(-1),
+	m_yaw(0),
+	m_properties_sent(true),
+	m_armor_groups_sent(false),
+	m_animation_range(0,0),
+	m_animation_speed(0),
+	m_animation_blend(0),
+	m_animation_loop(true),
+	m_animation_sent(false),
+	m_bone_position_sent(false),
+	m_attachment_parent_id(0),
+	m_attachment_sent(false)
+{
+	// Initialize something to armor groups
+	m_armor_groups["fleshy"] = 100;
+}
 /*
 	LuaEntitySAO
 */
@@ -125,29 +138,17 @@ LuaEntitySAO::LuaEntitySAO(ServerEnvironment *env, v3f pos,
 	m_registered(false),
 	m_velocity(0,0,0),
 	m_acceleration(0,0,0),
-	m_properties_sent(true),
 	m_last_sent_yaw(0),
 	m_last_sent_position(0,0,0),
 	m_last_sent_velocity(0,0,0),
 	m_last_sent_position_timer(0),
-	m_last_sent_move_precision(0),
-	m_armor_groups_sent(false),
-	m_animation_speed(0),
-	m_animation_blend(0),
-	m_animation_loop(true),
-	m_animation_sent(false),
-	m_bone_position_sent(false),
-	m_attachment_parent_id(0),
-	m_attachment_sent(false)
+	m_last_sent_move_precision(0)
 {
 	// Only register type if no environment supplied
 	if(env == NULL){
 		ServerActiveObject::registerType(getType(), create);
 		return;
 	}
-
-	// Initialize something to armor groups
-	m_armor_groups["fleshy"] = 100;
 }
 
 LuaEntitySAO::~LuaEntitySAO()
@@ -565,7 +566,7 @@ void LuaEntitySAO::setArmorGroups(const ItemGroupList &armor_groups)
 	m_armor_groups_sent = false;
 }
 
-ItemGroupList LuaEntitySAO::getArmorGroups()
+const ItemGroupList &LuaEntitySAO::getArmorGroups()
 {
 	return m_armor_groups;
 }
@@ -635,7 +636,7 @@ void LuaEntitySAO::removeAttachmentChild(int child_id)
 	m_attachment_child_ids.erase(child_id);
 }
 
-UNORDERED_SET<int> LuaEntitySAO::getAttachmentChildIds()
+const UNORDERED_SET<int> &LuaEntitySAO::getAttachmentChildIds()
 {
 	return m_attachment_child_ids;
 }
@@ -732,7 +733,8 @@ void LuaEntitySAO::sendPosition(bool do_interpolate, bool is_movement_end)
 	m_messages_out.push(aom);
 }
 
-bool LuaEntitySAO::getCollisionBox(aabb3f *toset) {
+bool LuaEntitySAO::getCollisionBox(aabb3f *toset) const
+{
 	if (m_prop.physical)
 	{
 		//update collision box
@@ -748,7 +750,8 @@ bool LuaEntitySAO::getCollisionBox(aabb3f *toset) {
 	return false;
 }
 
-bool LuaEntitySAO::collideWithObjects(){
+bool LuaEntitySAO::collideWithObjects() const
+{
 	return m_prop.collideWithObjects;
 }
 
@@ -770,16 +773,7 @@ PlayerSAO::PlayerSAO(ServerEnvironment *env_, u16 peer_id_, bool is_singleplayer
 	m_nocheat_dig_time(0),
 	m_wield_index(0),
 	m_position_not_sent(false),
-	m_armor_groups_sent(false),
-	m_properties_sent(true),
 	m_is_singleplayer(is_singleplayer),
-	m_animation_speed(0),
-	m_animation_blend(0),
-	m_animation_loop(true),
-	m_animation_sent(false),
-	m_bone_position_sent(false),
-	m_attachment_parent_id(0),
-	m_attachment_sent(false),
 	m_breath(PLAYER_MAX_BREATH),
 	m_pitch(0),
 	m_fov(0),
@@ -793,7 +787,6 @@ PlayerSAO::PlayerSAO(ServerEnvironment *env_, u16 peer_id_, bool is_singleplayer
 	m_physics_override_sent(false)
 {
 	assert(m_peer_id != 0);	// pre-condition
-	m_armor_groups["fleshy"] = 100;
 
 	m_prop.hp_max = PLAYER_MAX_HP;
 	m_prop.physical = false;
@@ -828,6 +821,11 @@ void PlayerSAO::initialize(RemotePlayer *player, const std::set<std::string> &pr
 	m_inventory = &m_player->inventory;
 }
 
+v3f PlayerSAO::getEyeOffset() const
+{
+	return v3f(0, BS * 1.625f, 0);
+}
+
 std::string PlayerSAO::getDescription()
 {
 	return std::string("player ") + m_player->getName();
@@ -1282,7 +1280,7 @@ void PlayerSAO::setArmorGroups(const ItemGroupList &armor_groups)
 	m_armor_groups_sent = false;
 }
 
-ItemGroupList PlayerSAO::getArmorGroups()
+const ItemGroupList &PlayerSAO::getArmorGroups()
 {
 	return m_armor_groups;
 }
@@ -1354,7 +1352,7 @@ void PlayerSAO::removeAttachmentChild(int child_id)
 	m_attachment_child_ids.erase(child_id);
 }
 
-UNORDERED_SET<int> PlayerSAO::getAttachmentChildIds()
+const UNORDERED_SET<int> &PlayerSAO::getAttachmentChildIds()
 {
 	return m_attachment_child_ids;
 }
@@ -1512,15 +1510,10 @@ bool PlayerSAO::checkMovementCheat()
 	return cheated;
 }
 
-bool PlayerSAO::getCollisionBox(aabb3f *toset)
+bool PlayerSAO::getCollisionBox(aabb3f *toset) const
 {
 	*toset = aabb3f(-BS * 0.30, 0.0, -BS * 0.30, BS * 0.30, BS * 1.75, BS * 0.30);
 	toset->MinEdge += m_base_position;
 	toset->MaxEdge += m_base_position;
 	return true;
 }
-
-bool PlayerSAO::collideWithObjects()
-{
-	return true;
-}
diff --git a/src/content_sao.h b/src/content_sao.h
index 9c66068b3..d5e9b2cbf 100644
--- a/src/content_sao.h
+++ b/src/content_sao.h
@@ -24,14 +24,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "serverobject.h"
 #include "itemgroup.h"
 #include "object_properties.h"
-#include "constants.h"
 
 class UnitSAO: public ServerActiveObject
 {
 public:
-	UnitSAO(ServerEnvironment *env, v3f pos):
-			ServerActiveObject(env, pos),
-			m_hp(-1), m_yaw(0) {}
+	UnitSAO(ServerEnvironment *env, v3f pos);
 	virtual ~UnitSAO() {}
 
 	virtual void setYaw(const float yaw) { m_yaw = yaw; }
@@ -46,6 +43,29 @@ public:
 protected:
 	s16 m_hp;
 	float m_yaw;
+
+	bool m_properties_sent;
+	struct ObjectProperties m_prop;
+
+	ItemGroupList m_armor_groups;
+	bool m_armor_groups_sent;
+
+	v2f m_animation_range;
+	float m_animation_speed;
+	float m_animation_blend;
+	bool m_animation_loop;
+	bool m_animation_sent;
+
+	// Stores position and rotation for each bone name
+	UNORDERED_MAP<std::string, core::vector2d<v3f> > m_bone_position;
+	bool m_bone_position_sent;
+
+	int m_attachment_parent_id;
+	UNORDERED_SET<int> m_attachment_child_ids;
+	std::string m_attachment_bone;
+	v3f m_attachment_position;
+	v3f m_attachment_rotation;
+	bool m_attachment_sent;
 };
 
 /*
@@ -81,7 +101,7 @@ public:
 	void setHP(s16 hp);
 	s16 getHP() const;
 	void setArmorGroups(const ItemGroupList &armor_groups);
-	ItemGroupList getArmorGroups();
+	const ItemGroupList &getArmorGroups();
 	void setAnimation(v2f frame_range, float frame_speed, float frame_blend, bool frame_loop);
 	void getAnimation(v2f *frame_range, float *frame_speed, float *frame_blend, bool *frame_loop);
 	void setBonePosition(const std::string &bone, v3f position, v3f rotation);
@@ -90,7 +110,7 @@ public:
 	void getAttachment(int *parent_id, std::string *bone, v3f *position, v3f *rotation);
 	void addAttachmentChild(int child_id);
 	void removeAttachmentChild(int child_id);
-	UNORDERED_SET<int> getAttachmentChildIds();
+	const UNORDERED_SET<int> &getAttachmentChildIds();
 	ObjectProperties* accessObjectProperties();
 	void notifyObjectPropertiesModified();
 	/* LuaEntitySAO-specific */
@@ -103,8 +123,8 @@ public:
 	void setSprite(v2s16 p, int num_frames, float framelength,
 			bool select_horiz_by_yawpitch);
 	std::string getName();
-	bool getCollisionBox(aabb3f *toset);
-	bool collideWithObjects();
+	bool getCollisionBox(aabb3f *toset) const;
+	bool collideWithObjects() const;
 private:
 	std::string getPropertyPacket();
 	void sendPosition(bool do_interpolate, bool is_movement_end);
@@ -112,36 +132,15 @@ private:
 	std::string m_init_name;
 	std::string m_init_state;
 	bool m_registered;
-	struct ObjectProperties m_prop;
 
 	v3f m_velocity;
 	v3f m_acceleration;
 
-	ItemGroupList m_armor_groups;
-
-	bool m_properties_sent;
 	float m_last_sent_yaw;
 	v3f m_last_sent_position;
 	v3f m_last_sent_velocity;
 	float m_last_sent_position_timer;
 	float m_last_sent_move_precision;
-	bool m_armor_groups_sent;
-
-	v2f m_animation_range;
-	float m_animation_speed;
-	float m_animation_blend;
-	bool m_animation_loop;
-	bool m_animation_sent;
-
-	UNORDERED_MAP<std::string, core::vector2d<v3f> > m_bone_position;
-	bool m_bone_position_sent;
-
-	int m_attachment_parent_id;
-	UNORDERED_SET<int> m_attachment_child_ids;
-	std::string m_attachment_bone;
-	v3f m_attachment_position;
-	v3f m_attachment_rotation;
-	bool m_attachment_sent;
 };
 
 /*
@@ -235,7 +234,7 @@ public:
 	u16 getBreath() const { return m_breath; }
 	void setBreath(const u16 breath, bool send = true);
 	void setArmorGroups(const ItemGroupList &armor_groups);
-	ItemGroupList getArmorGroups();
+	const ItemGroupList &getArmorGroups();
 	void setAnimation(v2f frame_range, float frame_speed, float frame_blend, bool frame_loop);
 	void getAnimation(v2f *frame_range, float *frame_speed, float *frame_blend, bool *frame_loop);
 	void setBonePosition(const std::string &bone, v3f position, v3f rotation);
@@ -244,7 +243,7 @@ public:
 	void getAttachment(int *parent_id, std::string *bone, v3f *position, v3f *rotation);
 	void addAttachmentChild(int child_id);
 	void removeAttachmentChild(int child_id);
-	UNORDERED_SET<int> getAttachmentChildIds();
+	const UNORDERED_SET<int> &getAttachmentChildIds();
 	ObjectProperties* accessObjectProperties();
 	void notifyObjectPropertiesModified();
 
@@ -315,13 +314,13 @@ public:
 		m_is_singleplayer = is_singleplayer;
 	}
 
-	bool getCollisionBox(aabb3f *toset);
-	bool collideWithObjects();
+	bool getCollisionBox(aabb3f *toset) const;
+	bool collideWithObjects() const { return true; }
 
 	void initialize(RemotePlayer *player, const std::set<std::string> &privs);
 
 	v3f getEyePosition() const { return m_base_position + getEyeOffset(); }
-	v3f getEyeOffset() const { return v3f(0, BS * 1.625f, 0); }
+	v3f getEyeOffset() const;
 
 private:
 	std::string getPropertyPacket();
@@ -346,31 +345,11 @@ private:
 
 	int m_wield_index;
 	bool m_position_not_sent;
-	ItemGroupList m_armor_groups;
-	bool m_armor_groups_sent;
 
-	bool m_properties_sent;
-	struct ObjectProperties m_prop;
 	// Cached privileges for enforcement
 	std::set<std::string> m_privs;
 	bool m_is_singleplayer;
 
-	v2f m_animation_range;
-	float m_animation_speed;
-	float m_animation_blend;
-	bool m_animation_loop;
-	bool m_animation_sent;
-
-	// Stores position and rotation for each bone name
-	UNORDERED_MAP<std::string, core::vector2d<v3f> > m_bone_position;
-	bool m_bone_position_sent;
-
-	int m_attachment_parent_id;
-	UNORDERED_SET<int> m_attachment_child_ids;
-	std::string m_attachment_bone;
-	v3f m_attachment_position;
-	v3f m_attachment_rotation;
-	bool m_attachment_sent;
 	u16 m_breath;
 	f32 m_pitch;
 	f32 m_fov;
diff --git a/src/script/lua_api/l_object.cpp b/src/script/lua_api/l_object.cpp
index cfdceb28e..84d14d521 100644
--- a/src/script/lua_api/l_object.cpp
+++ b/src/script/lua_api/l_object.cpp
@@ -137,8 +137,8 @@ int ObjectRef::l_remove(lua_State *L)
 	if (co->getType() == ACTIVEOBJECT_TYPE_PLAYER)
 		return 0;
 
-	UNORDERED_SET<int> child_ids = co->getAttachmentChildIds();
-	UNORDERED_SET<int>::iterator it;
+	const UNORDERED_SET<int> &child_ids = co->getAttachmentChildIds();
+	UNORDERED_SET<int>::const_iterator it;
 	for (it = child_ids.begin(); it != child_ids.end(); ++it) {
 		// Child can be NULL if it was deleted earlier
 		if (ServerActiveObject *child = env->getActiveObject(*it))
@@ -396,8 +396,7 @@ int ObjectRef::l_get_armor_groups(lua_State *L)
 	if (co == NULL)
 		return 0;
 	// Do it
-	ItemGroupList groups = co->getArmorGroups();
-	push_groups(L, groups);
+	push_groups(L, co->getArmorGroups());
 	return 1;
 }
 
diff --git a/src/serverobject.h b/src/serverobject.h
index 9884eb0a1..9e8b5a779 100644
--- a/src/serverobject.h
+++ b/src/serverobject.h
@@ -146,8 +146,8 @@ public:
 
 	virtual void setArmorGroups(const ItemGroupList &armor_groups)
 	{}
-	virtual ItemGroupList getArmorGroups()
-	{ return ItemGroupList(); }
+	virtual const ItemGroupList &getArmorGroups()
+	{ static const ItemGroupList rv; return rv; }
 	virtual void setPhysicsOverride(float physics_override_speed, float physics_override_jump, float physics_override_gravity)
 	{}
 	virtual void setAnimation(v2f frames, float frame_speed, float frame_blend, bool frame_loop)
@@ -166,8 +166,8 @@ public:
 	{}
 	virtual void removeAttachmentChild(int child_id)
 	{}
-	virtual UNORDERED_SET<int> getAttachmentChildIds()
-	{ return UNORDERED_SET<int>(); }
+	virtual const UNORDERED_SET<int> &getAttachmentChildIds()
+	{ static const UNORDERED_SET<int> rv; return rv; }
 	virtual ObjectProperties* accessObjectProperties()
 	{ return NULL; }
 	virtual void notifyObjectPropertiesModified()