@@ -46,9 +46,9 @@ testing =
 
 	# local
 	jaraco.itertools
-	func-timeout
 	jaraco.functools
 	more_itertools
+	big-O
 
 docs =
 	# upstream
 
@@ -10,13 +10,13 @@
 import unittest
 import zipfile
 
+import big_o
 import jaraco.itertools
 from jaraco.functools import compose
 
 import zipp
 
 from ._test_params import parameterize, Invoked
-from ._func_timeout_compat import set_timeout
 
 
 consume = tuple
@@ -336,10 +336,16 @@ def test_joinpath_constant_time(self):
         # Check the file iterated all items
         assert entries.count == self.HUGE_ZIPFILE_NUM_ENTRIES
 
-    @set_timeout(3)
     def test_implied_dirs_performance(self):
-        data = ['/'.join(string.ascii_lowercase + str(n)) for n in range(10000)]
-        consume(zipp.CompleteDirs._implied_dirs(data))
+        best, others = big_o.big_o(
+            compose(consume, zipp.CompleteDirs._implied_dirs),
+            lambda size: [
+                '/'.join(string.ascii_lowercase + str(n)) for n in range(size)
+            ],
+            max_n=1000,
+            min_n=1,
+        )
+        assert best.__class__ is big_o.complexities.Linear
 
     @pass_alpharep
     def test_read_does_not_close(self, alpharep):