fix(proxy): reduce SSL connection overhead by setting TCP_NODELAY

Set TCP_NODELAY on both the client-facing and proxy-to-PostgreSQL sockets
to disable Nagle's algorithm. PostgreSQL's connection startup involves rapid
small-message exchanges (auth, parameter status, ready-for-query), and with
SSL there are additional round trips for the SSLRequest handshake. Nagle's
buffering was delaying these small packets by up to 40ms each, compounding
into significant latency for workloads that open many short-lived connections.

Measured improvement on 101 connections x 3 queries: SSL overhead reduced
from +6s to +2s vs no-SSL baseline. Per-query overhead with connection reuse
is unaffected (remains ~0s).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: nik-localstack

postgresql_proxy/proxy.py

@@ -71,6 +71,7 @@ def _create_pg_connection(self, address, context):
         redirect_config = self.instance_config.redirect
 
         pg_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        pg_sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
         pg_sock.connect((redirect_config.host, redirect_config.port))
         pg_sock.setblocking(False)
 
@@ -130,6 +131,7 @@ def accept_wrapper(self, sock: socket.socket):
 
         # Accept the raw connection
         clientsocket, address = sock.accept()
+        clientsocket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
         # On macOS, accepted sockets inherit O_NONBLOCK from the listening socket.
         # SSL negotiation uses blocking recv, so we must set blocking explicitly here.
         clientsocket.setblocking(True)