diff --git a/swh/core/api/__init__.py b/swh/core/api/__init__.py
--- a/swh/core/api/__init__.py
+++ b/swh/core/api/__init__.py
@@ -159,6 +159,12 @@
         base_url = url if url.endswith('/') else url + '/'
         self.url = base_url
         self.session = requests.Session()
+        adapter = requests.adapters.HTTPAdapter(
+            max_retries=kwargs.get('max_retries', 3),
+            pool_connections=kwargs.get('pool_connections', 20),
+            pool_maxsize=kwargs.get('pool_maxsize', 100))
+        self.session.mount(self.url, adapter)
+
         self.timeout = timeout
         self.chunk_size = chunk_size
 
diff --git a/swh/core/api/tests/test_api.py b/swh/core/api/tests/test_api.py
--- a/swh/core/api/tests/test_api.py
+++ b/swh/core/api/tests/test_api.py
@@ -72,7 +72,10 @@
 
             def __init__(self, *args, **kwargs):
                 super().__init__(*args, **kwargs)
-                self.session.mount('mock', adapter)
+                # we need to mount the mock adapter on the base url to override
+                # SWHRemoteAPI's mechanism that also mounts an HTTPAdapter
+                # (for configuration purpose)
+                self.session.mount('mock://example.com/', adapter)
 
         c = Testclient(url='mock://example.com/')
         res = c.test_endpoint('spam')