diff --git a/tests/test_crawler_subprocess.py b/tests/test_crawler_subprocess.py
index fe2f83161..02bac4b06 100644
--- a/tests/test_crawler_subprocess.py
+++ b/tests/test_crawler_subprocess.py
@@ -20,6 +20,10 @@ from tests.utils.decorators import coroutine_test
 if TYPE_CHECKING:
     from tests.mockserver.http import MockServer
 
+# Guards against a hung subprocess. Generous, because starting a script is
+# slow on PyPy, slower still with coverage measurement on.
+SCRIPT_TIMEOUT = 60
+
 
 class ScriptRunnerMixin(ABC):
     @property
@@ -220,7 +224,7 @@ class TestCrawlerProcessSubprocessBase(ScriptRunnerMixin):
     ) -> None:
         sig = signal.SIGINT if sys.platform != "win32" else signal.SIGBREAK  # type: ignore[attr-defined]
         args = self.get_script_args(script, "3", *extra_args)
-        p = PopenSpawn(args, timeout=5, env=get_script_run_env())
+        p = PopenSpawn(args, timeout=SCRIPT_TIMEOUT, env=get_script_run_env())
         p.expect_exact("Spider opened")
         p.expect_exact("Crawled (200)")
         p.kill(sig)
@@ -238,7 +242,7 @@ class TestCrawlerProcessSubprocessBase(ScriptRunnerMixin):
     async def _test_shutdown_forced(self, script: str = "sleeping.py") -> None:
         sig = signal.SIGINT if sys.platform != "win32" else signal.SIGBREAK  # type: ignore[attr-defined]
         args = self.get_script_args(script, "10")
-        p = PopenSpawn(args, timeout=5, env=get_script_run_env())
+        p = PopenSpawn(args, timeout=SCRIPT_TIMEOUT, env=get_script_run_env())
         p.expect_exact("Spider opened")
         p.expect_exact("Crawled (200)")
         p.kill(sig)
diff --git a/tests/test_downloaderslotssettings.py b/tests/test_downloaderslotssettings.py
index 9d58a6e09..6f323a15c 100644
--- a/tests/test_downloaderslotssettings.py
+++ b/tests/test_downloaderslotssettings.py
@@ -70,15 +70,14 @@ class TestCrawl:
         yield crawler.crawl(mockserver=self.mockserver)
         slots = crawler.engine.downloader.slots
         times = crawler.spider.times
-        tolerance = 0.3
+        # Downloading and processing a response add a roughly constant amount
+        # of time on top of the configured delay, so the margin is absolute.
+        # It stays well below the 1 second that separates the delays being
+        # compared, so a slot using the delay of another one still fails.
+        tolerance = 0.75
 
-        delays_real = {k: v[1] - v[0] for k, v in times.items()}
-        error_delta = {
-            k: 1 - min(delays_real[k], v.delay) / max(delays_real[k], v.delay)
-            for k, v in slots.items()
-        }
-
-        assert max(list(error_delta.values())) < tolerance
+        for slot, (first, second) in times.items():
+            assert abs((second - first) - slots[slot].delay) < tolerance
 
 
 @coroutine_test