diff --git a/README.rst b/README.rst
index 5cf41fe..f2c46bf 100644
--- a/README.rst
+++ b/README.rst
@@ -227,6 +227,8 @@ As a note on performance_, both dicts and OrderedDicts have the same scaling for
 Comments
 +++++++++++++++++++++++++++++++++++++++
 
+*Warning: in the next major version, comment parsing will be opt-in, not default anymore (for performance reasons). Update your code now to pass `ignore_comments=True` explicitly if you want comment parsing.*
+
 This package uses ``#`` and ``//`` for comments, which seem to be the most common conventions, though only the latter is valid javascript.
 
 For example, you could call ``loads`` on the following string::
diff --git a/json_tricks/_version.py b/json_tricks/_version.py
index 28aa50a..2da49a6 100644
--- a/json_tricks/_version.py
+++ b/json_tricks/_version.py
@@ -1,3 +1,3 @@
 
-VERSION = '3.15.0'
+VERSION = '3.15.1'
 
diff --git a/json_tricks/nonp.py b/json_tricks/nonp.py
index 0aafa95..39f1980 100644
--- a/json_tricks/nonp.py
+++ b/json_tricks/nonp.py
@@ -1,9 +1,9 @@
-
+import warnings
 from json import loads as json_loads
 from os import fsync
 from sys import exc_info
 
-from json_tricks.utils import is_py3, dict_default, gzip_compress, gzip_decompress
+from json_tricks.utils import is_py3, dict_default, gzip_compress, gzip_decompress, JsonTricksDeprecation
 from .utils import str_type, NoNumpyException  # keep 'unused' imports
 from .comment import strip_comments  # keep 'unused' imports
 #TODO @mark: imports removed?
@@ -176,7 +176,7 @@ def dump(obj, fp, sort_keys=None, cls=TricksEncoder, obj_encoders=DEFAULT_ENCODE
 	return txt
 
 
-def loads(string, preserve_order=True, ignore_comments=True, decompression=None, obj_pairs_hooks=DEFAULT_HOOKS,
+def loads(string, preserve_order=True, ignore_comments=None, decompression=None, obj_pairs_hooks=DEFAULT_HOOKS,
 		extra_obj_pairs_hooks=(), cls_lookup_map=None, allow_duplicates=True, conv_str_byte=False, **jsonkwargs):
 	"""
 	Convert a nested data structure to a json string.
@@ -212,8 +212,16 @@ def loads(string, preserve_order=True, ignore_comments=True, decompression=None,
 				'for example bytevar.encode("utf-8") if utf-8 is the encoding. Alternatively you can '
 				'force an attempt by passing conv_str_byte=True, but this may cause decoding issues.')
 					.format(type(string)))
-	if ignore_comments:
-		string = strip_comments(string)
+	if ignore_comments or ignore_comments is None:
+		new_string = strip_comments(string)
+		if ignore_comments is None and not getattr(loads, '_ignore_comments_warned', False) and string != new_string:
+			warnings.warn('`json_tricks.load(s)` stripped some comments, but `ignore_comments` was '
+				'not passed; in the next major release, the behaviour when `ignore_comments` is not '
+				'passed will change; it is recommended to explicitly pass `ignore_comments=True` if '
+				'you want to strip comments; see https://github.com/mverleg/pyjson_tricks/issues/74',
+				JsonTricksDeprecation)
+			loads._ignore_comments_warned = True
+		string = new_string
 	obj_pairs_hooks = tuple(obj_pairs_hooks)
 	_cih_instance.cls_lookup_map = cls_lookup_map or {}
 	_eih_instance.cls_lookup_map = cls_lookup_map or {}
@@ -222,7 +230,7 @@ def loads(string, preserve_order=True, ignore_comments=True, decompression=None,
 	return json_loads(string, object_pairs_hook=hook, **jsonkwargs)
 
 
-def load(fp, preserve_order=True, ignore_comments=True, decompression=None, obj_pairs_hooks=DEFAULT_HOOKS,
+def load(fp, preserve_order=True, ignore_comments=None, decompression=None, obj_pairs_hooks=DEFAULT_HOOKS,
 		extra_obj_pairs_hooks=(), cls_lookup_map=None, allow_duplicates=True, conv_str_byte=False, **jsonkwargs):
 	"""
 	Convert a nested data structure to a json string.
diff --git a/tests/test_bare.py b/tests/test_bare.py
index a213174..d1d3091 100644
--- a/tests/test_bare.py
+++ b/tests/test_bare.py
@@ -12,12 +12,13 @@
 from os.path import join
 from tempfile import mkdtemp
 
+from _pytest.recwarn import warns
 from pytest import raises, fail
 
 from json_tricks import fallback_ignore_unknown, DuplicateJsonKeyException
 from json_tricks.nonp import strip_comments, dump, dumps, load, loads, \
 	ENCODING
-from json_tricks.utils import is_py3, gzip_compress
+from json_tricks.utils import is_py3, gzip_compress, JsonTricksDeprecation
 from .test_class import MyTestCls, CustomEncodeCls, SubClass, SuperClass, SlotsBase, SlotsDictABC, SlotsStr, \
 	SlotsABCDict, SlotsABC
 
@@ -143,6 +144,12 @@ def test_file_path():
 }
 """
 
+test_object_for_comment_strings = {
+	"hello": "Wor#d", "Bye": "\"M#rk\"", "yes\\\"": 5,
+	"quote": "\"th#t's\" what she said",
+	"list": [1, 1, "#", "\"", "\\", 8], "dict": {"q": 7}
+}
+
 test_json_duplicates = """{"test": 42, "test": 37}"""
 
 
@@ -153,6 +160,45 @@ def test_strip_comments():
 	assert valid == test_json_without_comments.replace('#', '//')
 
 
+def test_ignore_comments_deprecation():
+	# https://github.com/mverleg/pyjson_tricks/issues/74
+
+	# First time should have deprecation warning
+	loads._ignore_comments_warned_ = False
+	with warns(JsonTricksDeprecation):
+		loads(test_json_with_comments)
+
+	# Second time there should be no warning
+	# noinspection PyTypeChecker
+	with warns(None) as captured:
+		loaded = loads(test_json_with_comments)
+	assert len(captured) == 0
+	assert loaded == test_object_for_comment_strings
+
+	# Passing a string without comments should not have a warning
+	loads._ignore_comments_warned_ = False
+	# noinspection PyTypeChecker
+	with warns(None) as captured:
+		loaded = loads(test_json_without_comments)
+	assert len(captured) == 0
+
+	# Passing True for argument explicitly should not have a warning
+	loads._ignore_comments_warned_ = False
+	# noinspection PyTypeChecker
+	with warns(None) as captured:
+		loaded = loads(test_json_with_comments, ignore_comments=True)
+	assert len(captured) == 0
+	assert loaded == test_object_for_comment_strings
+
+	# Passing False for argument explicitly should not have a warning
+	loads._ignore_comments_warned_ = False
+	# noinspection PyTypeChecker
+	with warns(None) as captured:
+		loaded = loads(test_json_without_comments, ignore_comments=False)
+	assert len(captured) == 0
+	assert loaded == test_object_for_comment_strings
+
+
 ordered_map = OrderedDict((
 	('elephant', None),
 	('chicken', None),
diff --git a/tests/test_np.py b/tests/test_np.py
index 22520c0..8b37308 100644
--- a/tests/test_np.py
+++ b/tests/test_np.py
@@ -11,7 +11,6 @@
 	float16, float32, float64, complex64, complex128, zeros, ndindex
 from numpy.core.umath import exp
 from numpy.testing import assert_equal
-from pytest import raises
 
 from json_tricks import numpy_encode
 from json_tricks.np import dump, dumps, load, loads