Improve AMD performance. (comfyanonymous#10302)

I honestly have no idea why this improves things but it does.

Author: comfyanonymous

comfy/model_management.py

@@ -332,6 +332,7 @@ def amd_min_version(device=None, min_rdna_version=0):
 SUPPORT_FP8_OPS = args.supports_fp8_compute
 try:
     if is_amd():
+        torch.backends.cudnn.enabled = False  # Seems to improve things a lot on AMD
         try:
             rocm_version = tuple(map(int, str(torch.version.hip).split(".")[:2]))
         except:
@@ -925,11 +926,7 @@ def vae_dtype(device=None, allowed_dtypes=[]):
         if d == torch.float16 and should_use_fp16(device):
             return d
 
-        # NOTE: bfloat16 seems to work on AMD for the VAE but is extremely slow in some cases compared to fp32
-        # slowness still a problem on pytorch nightly 2.9.0.dev20250720+rocm6.4 tested on RDNA3
-        # also a problem on RDNA4 except fp32 is also slow there.
-        # This is due to large bf16 convolutions being extremely slow.
-        if d == torch.bfloat16 and ((not is_amd()) or amd_min_version(device, min_rdna_version=4)) and should_use_bf16(device):
+        if d == torch.bfloat16 and should_use_bf16(device):
             return d
 
     return torch.float32