diff --git a/.travis.yml b/.travis.yml
index 807a03c..eff1591 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,25 +1,20 @@
 language: python
 python:
-  - "2.7"
-  - "3.4"
   - "3.5"
   - "3.6"
+  - "3.7"
+  - "3.8"
 env:
   - DJANGO_VERSION=""
-  - DJANGO_VERSION=">=1.8,<1.9"
-  - DJANGO_VERSION=">=1.9,<1.10"
-  - DJANGO_VERSION=">=1.10,<1.11"
   - DJANGO_VERSION=">=1.11,<2"
   - DJANGO_VERSION=">=2,<2.1"
   - DJANGO_VERSION=">=2.1,<2.2"
+  - DJANGO_VERSION=">=2.2,<3"
+  - DJANGO_VERSION=">=3,<3.1"
 matrix:
   exclude:
-    - python: "2.7"
-      env: DJANGO_VERSION=">=2,<2.1"
-    - python: "2.7"
-      env: DJANGO_VERSION=">=2.1,<2.2"
-    - python: "3.4"
-      env: DJANGO_VERSION=">=2.1,<2.2"
+    - python: "3.5"
+      env: DJANGO_VERSION=">=3,<3.1"
 install:
   - pip install codecov $([ -n "$DJANGO_VERSION" ] && echo "Django$DJANGO_VERSION")
 script:
diff --git a/optimize_later/core.py b/optimize_later/core.py
index 1c2cc31..2e0117f 100644
--- a/optimize_later/core.py
+++ b/optimize_later/core.py
@@ -1,17 +1,16 @@
 import inspect
 import logging
 import os
-import time
 from copy import copy
 from functools import wraps
 from numbers import Number
+from time import perf_counter
 
 from optimize_later.config import global_callback
 from optimize_later.utils import NoArgDecoratorMeta, with_metaclass
 from optimize_later import utils
 
 log = logging.getLogger(__name__.rpartition('.')[0] or __name__)
-timer = [time.time, time.clock][os.name == 'nt']
 
 
 def _generate_default_name():
@@ -39,11 +38,11 @@ class OptimizeBlock(object):
 
     def __enter__(self):
         assert self.start is None, 'Do not reuse blocks.'
-        self.start = timer()
+        self.start = perf_counter()
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):
-        self.end = timer()
+        self.end = perf_counter()
         self.delta = self.end - self.start
 
     def short(self, precision=3):
@@ -115,11 +114,11 @@ class optimize_later(with_metaclass(NoArgDecoratorMeta)):
 
     def __enter__(self):
         assert self.start is None, 'Do not reuse optimize_later objects.'
-        self.start = timer()
+        self.start = perf_counter()
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):
-        self.end = timer()
+        self.end = perf_counter()
         self.delta = self.end - self.start
         if self.delta >= self.limit:
             self._report()