diff --git a/warcprox/controller.py b/warcprox/controller.py
index efa7885..dabbf6a 100644
--- a/warcprox/controller.py
+++ b/warcprox/controller.py
@@ -398,18 +398,14 @@ class WarcproxController(object):
                     'aggregate performance profile of %s proxy threads:\n%s',
                     len(files), buf.getvalue())
 
-            # warc writer threads
-            files = []
-            for wwt in self.warc_writer_threads:
-                file = os.path.join(tmpdir, '%s.dat' % wwt.ident)
-                wwt.profiler.dump_stats(file)
-                files.append(file)
-
-            buf = io.StringIO()
-            stats = pstats.Stats(*files, stream=buf)
-            stats.sort_stats('cumulative')
-            stats.print_stats(0.1)
-            self.logger.notice(
-                    'aggregate performance profile of %s warc writer threads:\n%s',
-                    len(self.warc_writer_threads), buf.getvalue())
-
+            # postfetch processors
+            for processor in self._postfetch_chain:
+                file = os.path.join(tmpdir, '%s.dat' % processor.ident)
+                processor.profiler.dump_stats(file)
+                buf = io.StringIO()
+                stats = pstats.Stats(file, stream=buf)
+                stats.sort_stats('cumulative')
+                stats.print_stats(0.1)
+                self.logger.notice(
+                        'performance profile of %s:\n%s', processor,
+                        buf.getvalue())
diff --git a/warcprox/mitmproxy.py b/warcprox/mitmproxy.py
index c42fb68..608cc75 100644
--- a/warcprox/mitmproxy.py
+++ b/warcprox/mitmproxy.py
@@ -62,6 +62,8 @@ except ImportError:
 import concurrent.futures
 import urlcanon
 import time
+import collections
+import cProfile
 
 class ProxyingRecorder(object):
     """
@@ -561,14 +563,14 @@ class PooledMitmProxy(PooledMixIn, MitmProxy):
     # See also https://blog.dubbelboer.com/2012/04/09/syn-cookies.html
     request_queue_size = 4096
 
-    def __init__(self, max_threads, options=warcprox.Options()):
+    def __init__(self, options=warcprox.Options()):
         if options.max_threads:
             self.logger.info(
-                    "max_threads=%s set by command line option",
+                    'max_threads=%s set by command line option',
                     options.max_threads)
 
         PooledMixIn.__init__(self, options.max_threads)
-        self.profilers = {}
+        self.profilers = collections.defaultdict(cProfile.Profile)
 
         if options.profile:
             self.process_request_thread = self._profile_process_request_thread
@@ -576,9 +578,6 @@ class PooledMitmProxy(PooledMixIn, MitmProxy):
             self.process_request_thread = self._process_request_thread
 
     def _profile_process_request_thread(self, request, client_address):
-        if not threading.current_thread().ident in self.profilers:
-            import cProfile
-            self.profilers[threading.current_thread().ident] = cProfile.Profile()
         profiler = self.profilers[threading.current_thread().ident]
         profiler.enable()
         self._process_request_thread(request, client_address)