diff --git a/lib/policy_service/application.ex b/lib/policy_service/application.ex
index 3159d25..48de43f 100644
--- a/lib/policy_service/application.ex
+++ b/lib/policy_service/application.ex
@@ -17,7 +17,7 @@ defmodule PolicyService.Application do
       PolicyServiceWeb.Telemetry,
       PolicyService.Repo,
       {DNSCluster, query: Application.get_env(:policy_service, :dns_cluster_query) || :ignore},
-      {Phoenix.PubSub, name: PolicyService.PubSub},
+      {Phoenix.PubSub, name: PolicyService.PubSub, pool_size: 1},
       PolicyServiceWeb.Endpoint
     ]
 
diff --git a/rel/vm.args.eex b/rel/vm.args.eex
new file mode 100644
index 0000000..649eb39
--- /dev/null
+++ b/rel/vm.args.eex
@@ -0,0 +1,45 @@
+## --- memory optimisation (embedded/low-RAM targets) ---
+
+## address-order best-fit for all allocators
++MBas aobf
++MHas aobf
++MPas aobf
++MDas aobf
++MFas aobf
+
+## disable carrier utilization limit
++MBacul 0
++MHacul 0
+
+## smaller carrier sizes
++MBsmbcs 64
++MBlmbcs 128
++MHsmbcs 64
++MHlmbcs 128
+
+## smaller main carrier
++MMscs 20
+
+## --- scheduler tuning ---
+
++S 1:1
++SDcpu 1:1
++SDio 1
+
+## --- resource limits ---
+
++t 100000
++P 50000
++Q 8192
+
+## --- general ---
+
++c false
++sbwt none
++sbwtdcpu none
++sbwtdio none
++swt very_low
++swtdcpu very_low
++swtdio very_low
++secio false
++K true