[fix]: resolve performance issue in multi-GPU inference

wan/utils/multitalk_utils.py

@@ -49,21 +49,25 @@ def torch_gc():
 def split_token_counts_and_frame_ids(T, token_frame, world_size, rank):
 
     S = T * token_frame
-    split_sizes = [S // world_size + (1 if i < S % world_size else 0) for i in range(world_size)]
-    start = sum(split_sizes[:rank])
+
+    # compute split sizes per rank
+    base = S // world_size
+    rem = S % world_size
+    split_sizes = torch.full((world_size,), base, dtype=torch.long)
+    split_sizes[:rem] += 1
+
+    start = split_sizes[:rank].sum()
     end = start + split_sizes[rank]
-    counts = [0] * T
-    for idx in range(start, end):
-        t = idx // token_frame
-        counts[t] += 1
-
-    counts_filtered = []
-    frame_ids = []
-    for t, c in enumerate(counts):
-        if c > 0:
-            counts_filtered.append(c)
-            frame_ids.append(t)
-    return counts_filtered, frame_ids
+
+    # vectorized mapping: global index -> frame id
+    idx = torch.arange(start, end, dtype=torch.long)
+    frame_ids = idx // token_frame
+
+    # unique counts
+    unique_frames, counts = torch.unique(frame_ids, return_counts=True)
+
+    # return as Python list (optional)
+    return counts.tolist(), unique_frames.tolist()
 
 
 def normalize_and_scale(column, source_range, target_range, epsilon=1e-8):