diff --git a/hw/dixie/default.nix b/hw/dixie/default.nix
index 38e1409..0b6649c 100644
--- a/hw/dixie/default.nix
+++ b/hw/dixie/default.nix
@@ -49,6 +49,11 @@ let
     ; at 96k incl. 5.5 GB weights), so 128k costs ~0.65 GB of the ~2.5 GB free.
     ctx-size = 131072
     parallel = 8
+    ; One scheduler step = up to batch-size prompt tokens, and every decoding slot gets one
+    ; token per step. At the 2048 default a step was ~2.4 s while Honcho's 10-28k prompts
+    ; prefilled, so 16-token guardian calls hit p90 10 s. The GPU already computes in
+    ; 512-token ubatches, so 512 keeps prefill throughput and makes steps ~0.6 s.
+    batch-size = 512
     ; Runaway guard carried over from straylight: helper tasks need short answers.
     reasoning-budget = 2048
     n-predict = 4096