diff --git a/database/leveldb.go b/database/leveldb.go
index 18b8b93f..8b065725 100644
--- a/database/leveldb.go
+++ b/database/leveldb.go
@@ -4,6 +4,9 @@ package database
 import (
 	"bytes"
 	"errors"
+	"io/ioutil"
+	"os"
+
 	"github.com/syndtr/goleveldb/leveldb"
 	"github.com/syndtr/goleveldb/leveldb/filter"
 	"github.com/syndtr/goleveldb/leveldb/opt"
@@ -16,11 +19,17 @@ var (
 	ErrNotFound = errors.New("key not found")
 )
 
+// StorageProcessor is a function to process one single storage entry
+type StorageProcessor func(key []byte, value []byte) error
+
 // Storage is an interface to KV storage
 type Storage interface {
+	CreateTemporary() (Storage, error)
 	Get(key []byte) ([]byte, error)
 	Put(key []byte, value []byte) error
 	Delete(key []byte) error
+	HasPrefix(prefix []byte) bool
+	ProcessByPrefix(prefix []byte, proc StorageProcessor) error
 	KeysByPrefix(prefix []byte) [][]byte
 	FetchByPrefix(prefix []byte) [][]byte
 	Close() error
@@ -28,6 +37,7 @@ type Storage interface {
 	StartBatch()
 	FinishBatch() error
 	CompactDB() error
+	Drop() error
 }
 
 type levelDB struct {
@@ -41,18 +51,24 @@ var (
 	_ Storage = &levelDB{}
 )
 
-func internalOpen(path string) (*leveldb.DB, error) {
+func internalOpen(path string, throttleCompaction bool) (*leveldb.DB, error) {
 	o := &opt.Options{
 		Filter:                 filter.NewBloomFilter(10),
 		OpenFilesCacheCapacity: 256,
 	}
 
+	if throttleCompaction {
+		o.CompactionL0Trigger = 32
+		o.WriteL0PauseTrigger = 96
+		o.WriteL0SlowdownTrigger = 64
+	}
+
 	return leveldb.OpenFile(path, o)
 }
 
 // OpenDB opens (creates) LevelDB database
 func OpenDB(path string) (Storage, error) {
-	db, err := internalOpen(path)
+	db, err := internalOpen(path, false)
 	if err != nil {
 		return nil, err
 	}
@@ -77,6 +93,20 @@ func RecoverDB(path string) error {
 	return nil
 }
 
+// CreateTemporary creates new DB of the same type in temp dir
+func (l *levelDB) CreateTemporary() (Storage, error) {
+	tempdir, err := ioutil.TempDir("", "aptly")
+	if err != nil {
+		return nil, err
+	}
+
+	db, err := internalOpen(tempdir, true)
+	if err != nil {
+		return nil, err
+	}
+	return &levelDB{db: db, path: tempdir}, nil
+}
+
 // Get key value from database
 func (l *levelDB) Get(key []byte) ([]byte, error) {
 	value, err := l.db.Get(key, nil)
@@ -152,6 +182,29 @@ func (l *levelDB) FetchByPrefix(prefix []byte) [][]byte {
 	return result
 }
 
+// HasPrefix checks whether it can find any key with given prefix and returns true if one exists
+func (l *levelDB) HasPrefix(prefix []byte) bool {
+	iterator := l.db.NewIterator(nil, nil)
+	defer iterator.Release()
+	return iterator.Seek(prefix) && bytes.HasPrefix(iterator.Key(), prefix)
+}
+
+// ProcessByPrefix iterates through all entries where key starts with prefix and calls
+// StorageProcessor on key value pair
+func (l *levelDB) ProcessByPrefix(prefix []byte, proc StorageProcessor) error {
+	iterator := l.db.NewIterator(nil, nil)
+	defer iterator.Release()
+
+	for ok := iterator.Seek(prefix); ok && bytes.HasPrefix(iterator.Key(), prefix); ok = iterator.Next() {
+		err := proc(iterator.Key(), iterator.Value())
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 // Close finishes DB work
 func (l *levelDB) Close() error {
 	if l.db == nil {
@@ -169,7 +222,7 @@ func (l *levelDB) ReOpen() error {
 	}
 
 	var err error
-	l.db, err = internalOpen(l.path)
+	l.db, err = internalOpen(l.path, false)
 	return err
 }
 
@@ -197,3 +250,12 @@ func (l *levelDB) FinishBatch() error {
 func (l *levelDB) CompactDB() error {
 	return l.db.CompactRange(util.Range{})
 }
+
+// Drop removes all the DB files (DANGEROUS!)
+func (l *levelDB) Drop() error {
+	if l.db != nil {
+		return errors.New("DB is still open")
+	}
+
+	return os.RemoveAll(l.path)
+}
diff --git a/database/leveldb_test.go b/database/leveldb_test.go
index 2119c388..155a3120 100644
--- a/database/leveldb_test.go
+++ b/database/leveldb_test.go
@@ -71,6 +71,29 @@ func (s *LevelDBSuite) TestGetPut(c *C) {
 	c.Assert(result, DeepEquals, value)
 }
 
+func (s *LevelDBSuite) TestTemporaryDelete(c *C) {
+	var (
+		key   = []byte("key")
+		value = []byte("value")
+	)
+
+	err := s.db.Put(key, value)
+	c.Assert(err, IsNil)
+
+	temp, err := s.db.CreateTemporary()
+	c.Assert(err, IsNil)
+
+	c.Check(s.db.HasPrefix([]byte(nil)), Equals, true)
+	c.Check(temp.HasPrefix([]byte(nil)), Equals, false)
+
+	err = temp.Put(key, value)
+	c.Assert(err, IsNil)
+	c.Check(temp.HasPrefix([]byte(nil)), Equals, true)
+
+	c.Assert(temp.Close(), IsNil)
+	c.Assert(temp.Drop(), IsNil)
+}
+
 func (s *LevelDBSuite) TestDelete(c *C) {
 	var (
 		key   = []byte("key")
@@ -107,10 +130,41 @@ func (s *LevelDBSuite) TestByPrefix(c *C) {
 	c.Check(s.db.FetchByPrefix([]byte{0x80}), DeepEquals, [][]byte{{0x01}, {0x02}, {0x03}})
 	c.Check(s.db.KeysByPrefix([]byte{0x80}), DeepEquals, [][]byte{{0x80, 0x01}, {0x80, 0x02}, {0x80, 0x03}})
 
+	keys := [][]byte{}
+	values := [][]byte{}
+
+	c.Check(s.db.ProcessByPrefix([]byte{0x80}, func(k, v []byte) error {
+		keys = append(keys, append([]byte(nil), k...))
+		values = append(values, append([]byte(nil), v...))
+		return nil
+	}), IsNil)
+
+	c.Check(values, DeepEquals, [][]byte{{0x01}, {0x02}, {0x03}})
+	c.Check(keys, DeepEquals, [][]byte{{0x80, 0x01}, {0x80, 0x02}, {0x80, 0x03}})
+
+	c.Check(s.db.ProcessByPrefix([]byte{0x80}, func(k, v []byte) error {
+		return ErrNotFound
+	}), Equals, ErrNotFound)
+
+	c.Check(s.db.ProcessByPrefix([]byte{0xa0}, func(k, v []byte) error {
+		return ErrNotFound
+	}), IsNil)
+
 	c.Check(s.db.FetchByPrefix([]byte{0xa0}), DeepEquals, [][]byte{})
 	c.Check(s.db.KeysByPrefix([]byte{0xa0}), DeepEquals, [][]byte{})
 }
 
+func (s *LevelDBSuite) TestHasPrefix(c *C) {
+	c.Check(s.db.HasPrefix([]byte(nil)), Equals, false)
+	c.Check(s.db.HasPrefix([]byte{0x80}), Equals, false)
+
+	s.db.Put([]byte{0x80, 0x01}, []byte{0x01})
+
+	c.Check(s.db.HasPrefix([]byte(nil)), Equals, true)
+	c.Check(s.db.HasPrefix([]byte{0x80}), Equals, true)
+	c.Check(s.db.HasPrefix([]byte{0x79}), Equals, false)
+}
+
 func (s *LevelDBSuite) TestBatch(c *C) {
 	var (
 		key    = []byte("key")
diff --git a/deb/collections.go b/deb/collections.go
index a34363b4..b7cbf2ea 100644
--- a/deb/collections.go
+++ b/deb/collections.go
@@ -1,8 +1,9 @@
 package deb
 
 import (
-	"github.com/smira/aptly/database"
 	"sync"
+
+	"github.com/smira/aptly/database"
 )
 
 // CollectionFactory is a single place to generate all desired collections
@@ -21,6 +22,13 @@ func NewCollectionFactory(db database.Storage) *CollectionFactory {
 	return &CollectionFactory{Mutex: &sync.Mutex{}, db: db}
 }
 
+// TemporaryDB creates new temporary DB
+//
+// DB should be closed/droped after being used
+func (factory *CollectionFactory) TemporaryDB() (database.Storage, error) {
+	return factory.db.CreateTemporary()
+}
+
 // PackageCollection returns (or creates) new PackageCollection
 func (factory *CollectionFactory) PackageCollection() *PackageCollection {
 	factory.Lock()
diff --git a/deb/contents.go b/deb/contents.go
index 514516e6..e3dc8eb7 100644
--- a/deb/contents.go
+++ b/deb/contents.go
@@ -1,75 +1,135 @@
 package deb
 
 import (
+	"bytes"
+	"errors"
 	"fmt"
-	"github.com/smira/aptly/aptly"
-	"github.com/smira/aptly/utils"
 	"io"
-	"sort"
-	"strings"
+
+	"github.com/smira/aptly/aptly"
+	"github.com/smira/aptly/database"
+	"github.com/smira/go-uuid/uuid"
 )
 
 // ContentsIndex calculates mapping from files to packages, with sorting and aggregation
 type ContentsIndex struct {
-	index map[string][]*Package
+	db     database.Storage
+	prefix []byte
 }
 
 // NewContentsIndex creates empty ContentsIndex
-func NewContentsIndex() *ContentsIndex {
+func NewContentsIndex(db database.Storage) *ContentsIndex {
 	return &ContentsIndex{
-		index: make(map[string][]*Package),
+		db:     db,
+		prefix: []byte(uuid.New()),
 	}
 }
 
 // Push adds package to contents index, calculating package contents as required
-func (index *ContentsIndex) Push(p *Package, packagePool aptly.PackagePool) {
+func (index *ContentsIndex) Push(p *Package, packagePool aptly.PackagePool) error {
 	contents := p.Contents(packagePool)
+	qualifiedName := []byte(p.QualifiedName())
 
 	for _, path := range contents {
-		index.index[path] = append(index.index[path], p)
+		// for performance reasons we only write to leveldb during push.
+		// merging of qualified names per path will be done in WriteTo
+		err := index.db.Put(append(append(append(index.prefix, []byte(path)...), byte(0)), qualifiedName...), nil)
+		if err != nil {
+			return err
+		}
 	}
+
+	return nil
 }
 
 // Empty checks whether index contains no packages
 func (index *ContentsIndex) Empty() bool {
-	return len(index.index) == 0
+	return !index.db.HasPrefix(index.prefix)
 }
 
 // WriteTo dumps sorted mapping of files to qualified package names
 func (index *ContentsIndex) WriteTo(w io.Writer) (int64, error) {
+	// For performance reasons push method wrote on key per path and package
+	// in this method we now need to merge all packages which have the same path
+	// and write it to contents index file
+
 	var n int64
 
-	paths := make([]string, len(index.index))
-
-	i := 0
-	for path := range index.index {
-		paths[i] = path
-		i++
-	}
-
-	sort.Strings(paths)
-
 	nn, err := fmt.Fprintf(w, "%s %s\n", "FILE", "LOCATION")
 	n += int64(nn)
 	if err != nil {
 		return n, err
 	}
 
-	for _, path := range paths {
-		packages := index.index[path]
-		parts := make([]string, 0, len(packages))
-		for i := range packages {
-			name := packages[i].QualifiedName()
-			if !utils.StrSliceHasItem(parts, name) {
-				parts = append(parts, name)
-			}
+	prefixLen := len(index.prefix)
+
+	var (
+		currentPath []byte
+		currentPkgs [][]byte
+	)
+
+	err = index.db.ProcessByPrefix(index.prefix, func(key []byte, value []byte) error {
+		// cut prefix
+		key = key[prefixLen:]
+
+		i := bytes.Index(key, []byte{0})
+		if i == -1 {
+			return errors.New("corrupted index entry")
 		}
-		nn, err = fmt.Fprintf(w, "%s %s\n", path, strings.Join(parts, ","))
+
+		path := key[:i]
+		pkg := key[i+1:]
+
+		if !bytes.Equal(path, currentPath) {
+			if currentPath != nil {
+				nn, err = w.Write(append(currentPath, ' '))
+				n += int64(nn)
+				if err != nil {
+					return err
+				}
+
+				nn, err = w.Write(bytes.Join(currentPkgs, []byte{','}))
+				n += int64(nn)
+				if err != nil {
+					return err
+				}
+
+				nn, err = w.Write([]byte{'\n'})
+				n += int64(nn)
+				if err != nil {
+					return err
+				}
+			}
+
+			currentPath = append([]byte(nil), path...)
+			currentPkgs = nil
+		}
+
+		currentPkgs = append(currentPkgs, append([]byte(nil), pkg...))
+
+		return nil
+	})
+
+	if err != nil {
+		return n, err
+	}
+
+	if currentPath != nil {
+		nn, err = w.Write(append(currentPath, ' '))
 		n += int64(nn)
 		if err != nil {
 			return n, err
 		}
+
+		nn, err = w.Write(bytes.Join(currentPkgs, []byte{','}))
+		n += int64(nn)
+		if err != nil {
+			return n, err
+		}
+
+		nn, err = w.Write([]byte{'\n'})
+		n += int64(nn)
 	}
 
-	return n, nil
+	return n, err
 }
diff --git a/deb/publish.go b/deb/publish.go
index 04dd221c..7f8ee3c4 100644
--- a/deb/publish.go
+++ b/deb/publish.go
@@ -469,6 +469,13 @@ func (p *PublishedRepo) Publish(packagePool aptly.PackagePool, publishedStorageP
 		return err
 	}
 
+	tempDB, err := collectionFactory.TemporaryDB()
+	if err != nil {
+		return err
+	}
+	defer tempDB.Close()
+	defer tempDB.Drop()
+
 	if progress != nil {
 		progress.Printf("Loading packages...\n")
 	}
@@ -563,7 +570,7 @@ func (p *PublishedRepo) Publish(packagePool aptly.PackagePool, publishedStorageP
 						contentIndex := contentIndexes[key]
 
 						if contentIndex == nil {
-							contentIndex = NewContentsIndex()
+							contentIndex = NewContentsIndex(tempDB)
 							contentIndexes[key] = contentIndex
 						}