diff --git a/patacrep/authors.py b/patacrep/authors.py
index 73f3fc7a..a1feda2e 100644
--- a/patacrep/authors.py
+++ b/patacrep/authors.py
@@ -64,7 +64,7 @@ def split_author_names(string):
             brace_count += 1
         if char == "{":
             brace_count -= 1
-    return string[:last_space], string[last_space:]
+    return string[last_space:], string[:last_space]
 
 
 def split_sep_author(string, sep):
@@ -162,23 +162,6 @@ def processauthors_clean_authors(authors_list):
             if author.lstrip()
             ]
 
-def processauthors_invert_names(authors_list):
-    """Move first names after last names
-
-    See docstring of processauthors() for more information.
-    """
-    dest = []
-    for author in authors_list:
-        first, last = split_author_names(author)
-        if first:
-            dest.append(ur"\indexauthor{{{first}}}{{{last}}}".format(
-                first=first.strip(),
-                last=last.strip(),
-                ))
-        else:
-            dest.append(last.lstrip())
-    return dest
-
 def processauthors(authors_string, after=None, ignore=None, sep=None):
     r"""Return a list of authors
 
@@ -210,10 +193,12 @@ def processauthors(authors_string, after=None, ignore=None, sep=None):
     4) Strings containing words of "ignore" are dropped.
     # ["William Blake", "Hubert Parry", The Royal\ Choir~of~Nowhere"]
 
-    5) First and last names are processed through LaTeX command \indexauthor
-        (which will, by default, invert first and last names).
-    # ["\indexauthor{William}{Blake}", "\indexauthor{Hubert}{Parry}",
-    # \indexthaor{The}{Royal\ Choir~of~Nowhere}"]
+    5) First and last names are splitted
+    # [
+    #   ("Blake", "William"),
+    #   ("Parry", "Hubert"),
+    #   ("Royal\ Choir~of~Nowhere", "The"),
+    # ]
     """
 
     if not sep:
@@ -223,8 +208,10 @@ def processauthors(authors_string, after=None, ignore=None, sep=None):
     if not ignore:
         ignore = []
 
-    return processauthors_invert_names(
-            processauthors_clean_authors(
+    return [
+            split_author_names(author)
+            for author
+            in processauthors_clean_authors(
                 processauthors_ignore_authors(
                     processauthors_remove_after(
                         processauthors_split_string(
@@ -235,5 +222,4 @@ def processauthors(authors_string, after=None, ignore=None, sep=None):
                         after),
                     ignore)
                 )
-            )
-
+            ]
diff --git a/patacrep/build.py b/patacrep/build.py
index dc5cdda0..13a173ab 100755
--- a/patacrep/build.py
+++ b/patacrep/build.py
@@ -13,6 +13,7 @@
 from patacrep import __DATADIR__, authors, content, errors
 from patacrep.index import process_sxd
 from patacrep.templates import TexRenderer
+from patacrep.songs import DataSubpath
 
 LOGGER = logging.getLogger(__name__)
 EOL = "\n"
@@ -75,7 +76,7 @@ def _set_datadir(self):
 
         self.config['datadir'] = abs_datadir
         self.config['_songdir'] = [
-                os.path.join(path, 'songs')
+                DataSubpath(path, 'songs')
                 for path in self.config['datadir']
                 ]
 
diff --git a/patacrep/content/cwd.py b/patacrep/content/cwd.py
index fff4c10e..338adb76 100755
--- a/patacrep/content/cwd.py
+++ b/patacrep/content/cwd.py
@@ -3,9 +3,8 @@
 
 """Change base directory before importing songs."""
 
-import os
-
 from patacrep.content import process_content
+from patacrep.songs import DataSubpath
 
 #pylint: disable=unused-argument
 def parse(keyword, config, argument, contentlist):
@@ -28,8 +27,8 @@ def parse(keyword, config, argument, contentlist):
     """
     old_songdir = config['_songdir']
     config['_songdir'] = (
-            [argument] +
-            [os.path.join(path, argument) for path in config['_songdir']] +
+            [DataSubpath("", argument)] +
+            [path.clone().join(argument) for path in config['_songdir']] +
             config['_songdir']
             )
     processed_content = process_content(contentlist, config)
diff --git a/patacrep/content/include.py b/patacrep/content/include.py
index 0b4a8967..45540db9 100644
--- a/patacrep/content/include.py
+++ b/patacrep/content/include.py
@@ -17,6 +17,10 @@
 LOGGER = logging.getLogger(__name__)
 
 def load_from_datadirs(path, config=None):
+    """Load 'path' from one of the datadirs.
+
+    Raise an exception if it was found if none of the datadirs of 'config'.
+    """
     for datadir in config.get("datadir", []):
         filepath = os.path.join(datadir, path)
         if os.path.exists(filepath):
diff --git a/patacrep/content/song.py b/patacrep/content/song.py
index 9965c861..18dbc252 100755
--- a/patacrep/content/song.py
+++ b/patacrep/content/song.py
@@ -35,7 +35,7 @@ def end_block(self, __context):
     def render(self, context):
         """Return the string that will render the song."""
         return ur'\input{{{}}}'.format(files.relpath(
-            self.path,
+            self.fullpath,
             os.path.dirname(context['filename'])
             ))
 
@@ -59,21 +59,28 @@ def parse(keyword, argument, contentlist, config):
         if contentlist:
             break
         contentlist = [
-                files.relpath(filename, songdir)
+                filename
                 for filename
                 in (
-                    files.recursive_find(songdir, "*.sg")
-                    + files.recursive_find(songdir, "*.is")
+                    files.recursive_find(songdir.fullpath, "*.sg")
+                    + files.recursive_find(songdir.fullpath, "*.is")
                     )
                 ]
     for elem in contentlist:
         before = len(songlist)
         for songdir in config['_songdir']:
-            for filename in glob.iglob(os.path.join(songdir, elem)):
-                LOGGER.debug('Parsing file "{}"…'.format(filename))
-                song = SongRenderer(filename, config)
-                songlist.append(song)
-                config["_languages"].update(song.languages)
+            if songdir.datadir and not os.path.isdir(songdir.datadir):
+                continue
+            with files.chdir(songdir.datadir):
+                for filename in glob.iglob(os.path.join(songdir.subpath, elem)):
+                    LOGGER.debug('Parsing file "{}"…'.format(filename))
+                    song = SongRenderer(
+                            songdir.datadir,
+                            filename,
+                            config,
+                            )
+                    songlist.append(song)
+                    config["_languages"].update(song.languages)
             if len(songlist) > before:
                 break
         if len(songlist) == before:
diff --git a/patacrep/content/sorted.py b/patacrep/content/sorted.py
index 12c63189..e9a5e677 100755
--- a/patacrep/content/sorted.py
+++ b/patacrep/content/sorted.py
@@ -33,8 +33,8 @@ def normalize_field(field):
     """Return a normalized field, it being a string or a list of strings."""
     if isinstance(field, basestring):
         return normalize_string(field)
-    elif isinstance(field, list):
-        return [normalize_string(string) for string in field]
+    elif isinstance(field, list) or isinstance(field, tuple):
+        return [normalize_field(string) for string in field]
 
 def key_generator(sort):
     """Return a function that returns the list of values used to sort the song.
@@ -50,7 +50,7 @@ def ordered_song_keys(song):
             if key == "@title":
                 field = song.unprefixed_titles
             elif key == "@path":
-                field = song.path
+                field = song.fullpath
             elif key == "by":
                 field = song.authors
             else:
@@ -60,7 +60,7 @@ def ordered_song_keys(song):
                     LOGGER.debug(
                             "Ignoring unknown key '{}' for song {}.".format(
                                 key,
-                                files.relpath(song.path),
+                                files.relpath(song.fullpath),
                                 )
                             )
                     field = u""
diff --git a/patacrep/content/tex.py b/patacrep/content/tex.py
index 1e18ecfd..ad109126 100755
--- a/patacrep/content/tex.py
+++ b/patacrep/content/tex.py
@@ -41,8 +41,11 @@ def parse(keyword, argument, contentlist, config):
     for filename in contentlist:
         checked_file = None
         for path in config['_songdir']:
-            if os.path.exists(os.path.join(path, filename)):
-                checked_file = os.path.relpath(os.path.join(path, filename))
+            if os.path.exists(os.path.join(path.fullpath, filename)):
+                checked_file = os.path.relpath(os.path.join(
+                    path.fullpath,
+                    filename,
+                    ))
                 break
         if not checked_file:
             LOGGER.warning(
diff --git a/patacrep/data/examples/.gitignore b/patacrep/data/examples/.gitignore
new file mode 100644
index 00000000..8c36c429
--- /dev/null
+++ b/patacrep/data/examples/.gitignore
@@ -0,0 +1 @@
+/.cache
diff --git a/patacrep/files.py b/patacrep/files.py
index 31cc4e2e..5ba23df2 100644
--- a/patacrep/files.py
+++ b/patacrep/files.py
@@ -4,6 +4,7 @@
 
 """File system utilities."""
 
+from contextlib import contextmanager
 import fnmatch
 import os
 
@@ -12,10 +13,14 @@ def recursive_find(root_directory, pattern):
 
     Return a list of files matching the pattern.
     """
+    if not os.path.isdir(root_directory):
+        return []
+
     matches = []
-    for root, _, filenames in os.walk(root_directory):
-        for filename in fnmatch.filter(filenames, pattern):
-            matches.append(os.path.join(root, filename))
+    with chdir(root_directory):
+        for root, _, filenames in os.walk(os.curdir):
+            for filename in fnmatch.filter(filenames, pattern):
+                matches.append(os.path.join(root, filename))
     return matches
 
 def relpath(path, start=None):
@@ -26,3 +31,22 @@ def relpath(path, start=None):
         return os.path.relpath(path, start)
     else:
         return os.path.abspath(path)
+
+@contextmanager
+def chdir(path):
+    """Locally change dir
+
+    Can be used as:
+
+        with chdir("some/directory"):
+            do_stuff()
+
+    """
+    olddir = os.getcwd()
+    if path:
+        os.chdir(path)
+        yield
+        os.chdir(olddir)
+    else:
+        yield
+
diff --git a/patacrep/index.py b/patacrep/index.py
index 27fa1eb1..63f3058d 100755
--- a/patacrep/index.py
+++ b/patacrep/index.py
@@ -22,18 +22,6 @@
 FIRST_LETTER_PATTERN = re.compile(ur"^(?:\{?\\\w+\}?)*[^\w]*(\w)", re.LOCALE)
 
 
-def sortkey(value):
-    """From a title, return something usable for sorting.
-
-    It handles locale (but
-    don't forget to call locale.setlocale(locale.LC_ALL, '')). It also handles
-    the sort with  latex escape sequences.
-    """
-    return locale.strxfrm(
-            encoding.unidecode(simpleparse(value).replace(' ', 'A')).lower()
-            )
-
-
 def process_sxd(filename):
     """Parse sxd file.
 
@@ -115,12 +103,18 @@ def _raw_add(self, key, number, link):
         No processing is done on data. It is added raw. See add() for a
         similar method with processing.
         """
-        first = self.get_first_letter(key)
+        first = self.get_first_letter(key[0])
         if not first in self.data.keys():
             self.data[first] = dict()
         if not key in self.data[first].keys():
-            self.data[first][key] = []
-        self.data[first][key].append({'num': number, 'link': link})
+            self.data[first][key] = {
+                    'sortingkey': [
+                        encoding.unidecode(simpleparse(item)).lower()
+                        for item in key
+                        ],
+                    'entries': [],
+                    }
+        self.data[first][key]['entries'].append({'num': number, 'link': link})
 
     def add(self, key, number, link):
         """Add a song to the list.
@@ -133,15 +127,15 @@ def add(self, key, number, link):
                 match = pattern.match(key)
                 if match:
                     self._raw_add(
-                            ur"\indextitle{{{}}}{{{}}}".format(
+                            (
                                 match.group(1).strip(),
-                                (match.group(2) + match.group(3)).strip(),
-                                ),
+                                (match.group(2) + match.group(3)).strip()
+                            ),
                             number,
                             link
                             )
                     return
-            self._raw_add(key, number, link)
+            self._raw_add((key, ""), number, link)
 
         if self.indextype == "AUTHOR":
             # Processing authors
@@ -155,10 +149,26 @@ def ref_to_str(ref):
         """Return the LaTeX code corresponding to the reference."""
         return ur'\hyperlink{{{0[link]}}}{{{0[num]}}}'.format(ref)
 
+    def key_to_str(self, key):
+        """Convert the key (title or author) to the LaTeX command rendering it.
+
+        """
+        if self.indextype == "AUTHOR":
+            if key[1]:
+                return ur"\indexauthor{{{first}}}{{{last}}}".format(
+                    first=key[1],
+                    last=key[0],
+                    )
+            else:
+                return key[0]
+
+        if self.indextype == "TITLE":
+            return ur"\indextitle{{{0[0]}}}{{{0[1]}}}".format(key)
+
     def entry_to_str(self, key, entry):
         """Return the LaTeX code corresponding to the entry."""
         return unicode(ur'\idxentry{{{0}}}{{{1}}}' + EOL).format(
-                key,
+                self.key_to_str(key),
                 ur'\\'.join([self.ref_to_str(ref) for ref in entry]),
                 )
 
@@ -168,9 +178,16 @@ def idxblock_to_str(self, letter, entries):
         Here, an index block is a letter, and all data beginning with this
         letter.
         """
+        def sortkey(key):
+            """Return something sortable for `entries[key]`."""
+            return [
+                    locale.strxfrm(item)
+                    for item
+                    in entries[key]['sortingkey']
+                    ]
         string = ur'\begin{idxblock}{' + letter + '}' + EOL
-        for key in sorted(entries.keys(), key=sortkey):
-            string += self.entry_to_str(key, entries[key])
+        for key in sorted(entries, key=sortkey):
+            string += self.entry_to_str(key, entries[key]['entries'])
         string += ur'\end{idxblock}' + EOL
         return string
 
diff --git a/patacrep/plastex.py b/patacrep/plastex.py
index b1c906b2..ecfa2d00 100644
--- a/patacrep/plastex.py
+++ b/patacrep/plastex.py
@@ -39,6 +39,7 @@ def simpleparse(text):
     """Parse a simple LaTeX string.
     """
     tex = TeX()
+    tex.disableLogging()
     tex.input(text)
     doc = tex.parse()
     return process_unbr_spaces(doc.textContent)
diff --git a/patacrep/songs.py b/patacrep/songs.py
index a3adc856..5f3a7d8c 100755
--- a/patacrep/songs.py
+++ b/patacrep/songs.py
@@ -3,19 +3,121 @@
 
 """Song management."""
 
+import errno
+import hashlib
+import logging
+import os
 import re
 
+try:
+    import cPickle as pickle
+except ImportError:
+    import pickle
+
 from patacrep.authors import processauthors
 from patacrep.plastex import parsetex
 
-# pylint: disable=too-few-public-methods
+LOGGER = logging.getLogger(__name__)
+
+def cached_name(datadir, filename):
+    """Return the filename of the cache version of the file."""
+    fullpath = os.path.abspath(os.path.join(datadir, '.cache', filename))
+    directory = os.path.dirname(fullpath)
+    try:
+        os.makedirs(directory)
+    except OSError as error:
+        if error.errno == errno.EEXIST and os.path.isdir(directory):
+            pass
+        else:
+            raise
+    return fullpath
+
+class DataSubpath(object):
+    """A path divided in two path: a datadir, and its subpath.
+
+    - This object can represent either a file or directory.
+    - If the datadir part is the empty string, it means that the represented
+      path does not belong to a datadir.
+    """
+
+    def __init__(self, datadir, subpath):
+        if os.path.isabs(subpath):
+            self.datadir = ""
+        else:
+            self.datadir = datadir
+        self.subpath = subpath
+
+    def __str__(self):
+        return os.path.join(self.datadir, self.subpath)
+
+    @property
+    def fullpath(self):
+        """Return the full path represented by self."""
+        return os.path.join(self.datadir, self.subpath)
+
+    def clone(self):
+        """Return a cloned object."""
+        return DataSubpath(self.datadir, self.subpath)
+
+    def join(self, path):
+        """Join "path" argument to self path.
+
+        Return self for commodity.
+        """
+        self.subpath = os.path.join(self.subpath, path)
+        return self
+
+# pylint: disable=too-few-public-methods, too-many-instance-attributes
 class Song(object):
     """Song management"""
 
-    def __init__(self, filename, config):
+    # Version format of cached song. Increment this number if we update
+    # information stored in cache.
+    CACHE_VERSION = 0
+
+    # List of attributes to cache
+    cached_attributes = [
+            "titles",
+            "unprefixed_titles",
+            "args",
+            "datadir",
+            "fullpath",
+            "subpath",
+            "languages",
+            "authors",
+            "_filehash",
+            "_version",
+            ]
+
+    def __init__(self, datadir, subpath, config):
+        self.fullpath = os.path.join(datadir, subpath)
+        if datadir:
+            # Only songs in datadirs are cached
+            self._filehash = hashlib.md5(
+                    open(self.fullpath, 'rb').read()
+                    ).hexdigest()
+            if os.path.exists(cached_name(datadir, subpath)):
+                try:
+                    cached = pickle.load(open(
+                        cached_name(datadir, subpath),
+                        'rb',
+                        ))
+                    if (
+                            cached['_filehash'] == self._filehash
+                            and cached['_version'] == self.CACHE_VERSION
+                            ):
+                        for attribute in self.cached_attributes:
+                            setattr(self, attribute, cached[attribute])
+                        return
+                except: # pylint: disable=bare-except
+                    LOGGER.warning("Could not use cached version of {}.".format(
+                        self.fullpath
+                        ))
+
         # Data extraction from the song with plastex
-        data = parsetex(filename)
+        data = parsetex(self.fullpath)
         self.titles = data['titles']
+        self.datadir = datadir
         self.unprefixed_titles = [
                 unprefixed_title(
                     title,
@@ -25,7 +127,7 @@ def __init__(self, filename, config):
                 in self.titles
                 ]
         self.args = data['args']
-        self.path = filename
+        self.subpath = subpath
         self.languages = data['languages']
         if "by" in self.args.keys():
             self.authors = processauthors(
@@ -35,8 +137,30 @@ def __init__(self, filename, config):
         else:
             self.authors = []
 
+        self._version = self.CACHE_VERSION
+        self._write_cache()
+
+    def _write_cache(self):
+        """If relevant, write a dumbed down version of self to the cache."""
+        if self.datadir:
+            cached = {}
+            for attribute in self.cached_attributes:
+                if attribute == "args":
+                    cached[attribute] = dict([
+                        (key, u"{}".format(value)) # Force conversion to unicode
+                        for (key, value)
+                        in self.args.iteritems()
+                        ])
+                else:
+                    cached[attribute] = getattr(self, attribute)
+            pickle.dump(
+                    cached,
+                    open(cached_name(self.datadir, self.subpath), 'wb'),
+                    protocol=-1
+                    )
+
     def __repr__(self):
-        return repr((self.titles, self.args, self.path))
+        return repr((self.titles, self.args, self.fullpath))
 
 def unprefixed_title(title, prefixes):
     """Remove the first prefix of the list in the beginning of title (if any).