diff --git a/tensorrt_llm/_torch/modules/fused_moe/routing.py b/tensorrt_llm/_torch/modules/fused_moe/routing.py
index 69498c96cfc3..db3de6ea7ad6 100644
--- a/tensorrt_llm/_torch/modules/fused_moe/routing.py
+++ b/tensorrt_llm/_torch/modules/fused_moe/routing.py
@@ -264,9 +264,9 @@ def noaux_tc(self, logits, e_score_correction_bias):
                         "The configuration is not supported by the fused routing kernel. We have to use the original pytorch implementation."
                     )
                 self.is_fused = False
-        elif (num_experts > 512 or (self.top_k > 8 and self.top_k != 22)
-              or (self.topk_group == 1 and self.top_k != 22)):
-            # We have special implementation for n_group == 1, top_k == 22 and num_experts == 512 for Nemotron Super v3.
+        elif num_experts > 512 or (self.top_k > 8 and self.top_k != 22):
+            # The fused noaux_tc_op kernel supports n_group==1 with top_k<=8
+            # or top_k==22, and num_experts<=512.
             if self.is_fused:
                 warnings.warn(
                     "The configuration is not supported by the fused routing kernel. We have to use the original pytorch implementation."
diff --git a/tensorrt_llm/_torch/modules/mamba/mamba2_mixer.py b/tensorrt_llm/_torch/modules/mamba/mamba2_mixer.py
index fdb5004495e3..23557ee2011c 100644
--- a/tensorrt_llm/_torch/modules/mamba/mamba2_mixer.py
+++ b/tensorrt_llm/_torch/modules/mamba/mamba2_mixer.py
@@ -245,6 +245,16 @@ def post_load_weights(self):
                 and self.norm.nvfp4_scale is None):
             self._try_attach_nvfp4_scale()
 
+        # Pre-expand A, D, dt_bias for the decode path.
+        self._A_expanded = repeat(self.A,
+                                  "h -> h p n",
+                                  p=self.head_dim,
+                                  n=self.d_state).to(dtype=torch.float32)
+        self._dt_bias_expanded = repeat(self.dt_bias,
+                                        "h -> h p",
+                                        p=self.head_dim)
+        self._D_expanded = repeat(self.D, "h -> h p", p=self.head_dim)
+
     def _try_attach_nvfp4_scale(self):
         """Attach input_scale from out_proj to norm for fused RMSNorm+Quant."""
 
@@ -471,10 +481,9 @@ def convert_dt():
                             g=self.tp_ngroups).contiguous()
             z_d = rearrange(z_d, "b (h p) -> b h p", p=self.head_dim)
 
-            A = repeat(self.A, "h -> h p n", p=self.head_dim,
-                       n=self.d_state).to(dtype=torch.float32)
-            dt_bias = repeat(self.dt_bias, "h -> h p", p=self.head_dim)
-            D = repeat(self.D, "h -> h p", p=self.head_dim)
+            A = self._A_expanded
+            dt_bias = self._dt_bias_expanded
+            D = self._D_expanded
             if is_target_verify:
                 intermediate_ssm_states = layer_cache.intermediate_ssm
                 x_d_mtp = x_d.view(