diff --git a/lark/lexer.py b/lark/lexer.py
index bcf09f1..0a46ee1 100644
--- a/lark/lexer.py
+++ b/lark/lexer.py
@@ -25,6 +25,8 @@ class UnexpectedInput(LexError):
         self.considered_rules = considered_rules
 
 class Token(Str):
+    __slots__ = ('type', 'pos_in_stream', 'value', 'line', 'column', 'end_line', 'end_column')
+
     def __new__(cls, type_, value, pos_in_stream=None, line=None, column=None):
         self = super(Token, cls).__new__(cls, value)
         self.type = type_
diff --git a/lark/parsers/grammar_analysis.py b/lark/parsers/grammar_analysis.py
index 9ad49ce..5cbd697 100644
--- a/lark/parsers/grammar_analysis.py
+++ b/lark/parsers/grammar_analysis.py
@@ -5,6 +5,8 @@ from ..grammar import Rule
 
 
 class RulePtr(object):
+    __slots__ = ('rule', 'index')
+
     def __init__(self, rule, index):
         assert isinstance(rule, Rule)
         assert index <= len(rule.expansion)