diff --git a/src/diffusers/models/autoencoders/autoencoder_kl_wan.py b/src/diffusers/models/autoencoders/autoencoder_kl_wan.py
index fe00d8c078ff..49cefcd8a142 100644
--- a/src/diffusers/models/autoencoders/autoencoder_kl_wan.py
+++ b/src/diffusers/models/autoencoders/autoencoder_kl_wan.py
@@ -749,6 +749,16 @@ def __init__(
         self.tile_sample_stride_height = 192
         self.tile_sample_stride_width = 192
 
+        # Precompute and cache conv counts for encoder and decoder for clear_cache speedup
+        self._cached_conv_counts = {
+            "decoder": sum(isinstance(m, WanCausalConv3d) for m in self.decoder.modules())
+            if self.decoder is not None
+            else 0,
+            "encoder": sum(isinstance(m, WanCausalConv3d) for m in self.encoder.modules())
+            if self.encoder is not None
+            else 0,
+        }
+
     def enable_tiling(
         self,
         tile_sample_min_height: Optional[int] = None,
@@ -801,18 +811,12 @@ def disable_slicing(self) -> None:
         self.use_slicing = False
 
     def clear_cache(self):
-        def _count_conv3d(model):
-            count = 0
-            for m in model.modules():
-                if isinstance(m, WanCausalConv3d):
-                    count += 1
-            return count
-
-        self._conv_num = _count_conv3d(self.decoder)
+        # Use cached conv counts for decoder and encoder to avoid re-iterating modules each call
+        self._conv_num = self._cached_conv_counts["decoder"]
         self._conv_idx = [0]
         self._feat_map = [None] * self._conv_num
         # cache encode
-        self._enc_conv_num = _count_conv3d(self.encoder)
+        self._enc_conv_num = self._cached_conv_counts["encoder"]
         self._enc_conv_idx = [0]
         self._enc_feat_map = [None] * self._enc_conv_num