--- a/hgsubversion/editor.py
+++ b/hgsubversion/editor.py
@@ -95,7 +95,7 @@ class RevisionData(object):
         self.clear()
 
     def clear(self):
-        self.store = FileStore()
+        self.store = FileStore(util.getfilestoresize(self.ui))
         self.added = set()
         self.deleted = {}
         self.rev = None

--- a/hgsubversion/help/subversion.rst
+++ b/hgsubversion/help/subversion.rst
@@ -302,6 +302,25 @@ settings:
     be included or excluded. See the documentation for ``hg convert`` for more
     information on filemaps.
 
+  ``hgsubversion.filestoresize``
+
+    Maximum amount of temporary edited files data to be kept in memory,
+    in megabytes. The replay and stupid mode pull data by retrieving
+    delta information from the subversion repository and applying it on
+    known files data. Since the order of file edits is driven by the
+    subversion delta information order, edited files cannot be committed
+    immediately and are kept until all of them have been processed for
+    each changeset. ``filestoresize`` defines the maximum amount of
+    files data to be kept in memory before falling back to storing them
+    in a temporary directory. This setting is important with
+    repositories containing many files or large ones as both the
+    application of deltas and Mercurial commit process require the whole
+    file data to be available in memory. By limiting the amount of
+    temporary data kept in memory, larger files can be retrieved, at the
+    price of slower disk operations. Set it to a negative value to
+    disable the fallback behaviour and keep everything in memory.
+    Default to 200.
+
   ``hgsubversion.username``, ``hgsubversion.password``
 
     Set the username or password for accessing Subversion repositories.

--- a/hgsubversion/stupid.py
+++ b/hgsubversion/stupid.py
@@ -235,7 +235,7 @@ except AttributeError:
 def patchrepo(ui, meta, parentctx, patchfp):
     if not svnbackend:
         return patchrepoold(ui, meta, parentctx, patchfp)
-    store = patch.filestore()
+    store = patch.filestore(util.getfilestoresize(ui))
     try:
         touched = set()
         backend = svnbackend(ui, meta.repo, parentctx, store)

--- a/hgsubversion/util.py
+++ b/hgsubversion/util.py
@@ -327,3 +327,12 @@ revsets = {
     'fromsvn': revset_fromsvn,
     'svnrev': revset_svnrev,
 }
+
+def getfilestoresize(ui):
+    """Return the replay or stupid file memory store size in megabytes or -1"""
+    size = ui.configint('hgsubversion', 'filestoresize', 200)
+    if size >= 0:
+        size = size*(2**20)
+    else:
+        size = -1
+    return size

--- a/tests/test_fetch_renames.py
+++ b/tests/test_fetch_renames.py
@@ -14,8 +14,11 @@ class TestFetchRenames(test_util.TestBas
                 w('%s: %r %r\n' % (f, fctx.data(), fctx.renamed()))
 
     def _test_rename(self, stupid):
-        repo = self._load_fixture_and_fetch('renames.svndump', stupid=stupid)
-        # self._debug_print_copies(repo)
+        config = {
+            'hgsubversion.filestoresize': '0',
+            }
+        repo = self._load_fixture_and_fetch('renames.svndump', stupid=stupid,
+                config=config)
 
         # Map revnum to mappings of dest name to (source name, dest content)
         copies = {

--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -333,8 +333,9 @@ class TestBase(unittest.TestCase):
             tarball.extract(entry, path)
         return path
 
-    def fetch(self, repo_path, subdir=None, stupid=False, layout='auto', startrev=0,
-              externals=None, noupdate=True, dest=None, rev=None):
+    def fetch(self, repo_path, subdir=None, stupid=False, layout='auto',
+            startrev=0, externals=None, noupdate=True, dest=None, rev=None,
+            config=None):
         if layout == 'single':
             if subdir is None:
                 subdir = 'trunk'
@@ -357,8 +358,11 @@ class TestBase(unittest.TestCase):
             cmd.append('--noupdate')
         if rev is not None:
             cmd.append('--rev=%s' % rev)
+        config = dict(config or {})
         if externals:
-            cmd[:0] = ['--config', 'hgsubversion.externals=%s' % externals]
+            config['hgsubversion.externals'] = str(externals)
+        for k,v in reversed(sorted(config.iteritems())):
+            cmd[:0] = ['--config', '%s=%s' % (k, v)]
 
         dispatch(cmd)