diff --git a/src/connectrpc/_compression.py b/src/connectrpc/_compression.py
index 7a5fe6d..077d633 100644
--- a/src/connectrpc/_compression.py
+++ b/src/connectrpc/_compression.py
@@ -29,7 +29,7 @@ def name(self) -> str:
         return "gzip"
 
     def compress(self, data: bytes | bytearray) -> bytes:
-        return gzip.compress(data)
+        return gzip.compress(data, compresslevel=6)
 
     def decompress(self, data: bytes | bytearray) -> bytes:
         return gzip.decompress(data)
@@ -45,7 +45,7 @@ def name(self) -> str:
             return "br"
 
         def compress(self, data: bytes | bytearray) -> bytes:
-            return brotli.compress(data)
+            return brotli.compress(data, quality=3)
 
         def decompress(self, data: bytes | bytearray) -> bytes:
             return brotli.decompress(data)