diff --git a/jedi/api/__init__.py b/jedi/api/__init__.py
index a22cb2ce..b543fee8 100644
--- a/jedi/api/__init__.py
+++ b/jedi/api/__init__.py
@@ -15,8 +15,7 @@ import sys
 
 from jedi.parser.python import load_grammar
 from jedi.parser.python import tree
-from jedi.parser.python.diff import FastParser
-from jedi.parser.utils import save_parser
+from jedi.parser.python import parse
 from jedi import debug
 from jedi import settings
 from jedi import common
@@ -133,10 +132,13 @@ class Script(object):
 
     @cache.memoize_method
     def _get_module_node(self):
-        parser = FastParser(self._grammar, self._source, self.path)
-        save_parser(self._grammar, self.path, parser, pickling=False)
-
-        return parser.get_root_node()
+        return parse(
+            code=self._source,
+            path=self.path,
+            grammar=self._grammar,
+            cache=True,
+            diff_cache=True,
+        )
 
     @cache.memoize_method
     def _get_module(self):
diff --git a/jedi/parser/python/__init__.py b/jedi/parser/python/__init__.py
index dfd8e734..c3085a40 100644
--- a/jedi/parser/python/__init__.py
+++ b/jedi/parser/python/__init__.py
@@ -7,8 +7,10 @@ from jedi._compatibility import FileNotFoundError
 from jedi.parser.pgen2.pgen import generate_grammar
 from jedi.parser.python.parser import Parser, ParserWithRecovery, \
     _remove_last_newline
+from jedi.parser.python.diff import DiffParser
 from jedi.parser.tokenize import source_tokens
 from jedi.parser import utils
+from jedi.common import splitlines
 
 
 _loaded_grammars = {}
@@ -93,14 +95,28 @@ def parse(code=None, path=None, grammar=None, error_recovery=True,
     kwargs = {}
     if error_recovery:
         parser = ParserWithRecovery
+        kwargs = dict(module_path=path)
     else:
         kwargs = dict(start_symbol=start_symbol)
         parser = Parser
+    # TODO add recovery
+    if diff_cache:
+        try:
+            parser_cache_item = utils.parser_cache[path]
+        except KeyError:
+            pass
+        else:
+            p = parser_cache_item.parser
+            lines = splitlines(code, keepends=True)
+            new_node = DiffParser(p).update(lines)
+            p._parsed = new_node
+            utils.save_parser(grammar, path, p, pickling=False)
+            return new_node
     p = parser(grammar, code, start_parsing=False, **kwargs)
     module = p.parse(tokens=tokens)
     if added_newline:
         _remove_last_newline(module)
 
-    if use_cache:
-        utils.save_parser(grammar, path, parser)
+    if use_cache or diff_cache:
+        utils.save_parser(grammar, path, p)
     return module
diff --git a/jedi/parser/python/diff.py b/jedi/parser/python/diff.py
index 27dc8462..ceb7e77d 100644
--- a/jedi/parser/python/diff.py
+++ b/jedi/parser/python/diff.py
@@ -12,7 +12,6 @@ from collections import namedtuple
 from jedi._compatibility import use_metaclass
 from jedi import settings
 from jedi.common import splitlines
-from jedi.parser.python import load_grammar
 from jedi.parser.python.parser import ParserWithRecovery, _remove_last_newline
 from jedi.parser.python.tree import EndMarker
 from jedi.parser.utils import parser_cache
@@ -138,6 +137,7 @@ def load_diff_parser(path, python_version=None):
 class NewDiffParser(object):
     def __init__(self, path, python_version=None):
         self._path = path
+        from jedi.parser.python import load_grammar
         grammar = load_grammar(version=python_version)
         self._parser = ParserWithRecovery(grammar)
         self._module = None
diff --git a/jedi/parser/utils.py b/jedi/parser/utils.py
index 2bdb767a..153450de 100644
--- a/jedi/parser/utils.py
+++ b/jedi/parser/utils.py
@@ -65,6 +65,7 @@ def load_parser(grammar, path):
     """
     p_time = os.path.getmtime(path) if path else None
     try:
+        # TODO Add grammar sha256
         parser_cache_item = parser_cache[path]
         if not path or p_time <= parser_cache_item.change_time:
             return parser_cache_item.parser
@@ -82,7 +83,7 @@ def save_parser(grammar, path, parser, pickling=True):
 
     item = ParserCacheItem(parser, p_time)
     parser_cache[path] = item
-    if settings.use_filesystem_cache and pickling:
+    if settings.use_filesystem_cache and pickling and path is not None:
         ParserPickling.save_parser(grammar, path, item)