[Misc] Small perf improvements (#6520)

vllm/model_executor/models/__init__.py

@@ -1,3 +1,4 @@
+import functools
 import importlib
 from typing import Dict, List, Optional, Type
 
@@ -98,6 +99,14 @@ _ROCM_PARTIALLY_SUPPORTED_MODELS: Dict[str, str] = {
 
 class ModelRegistry:
 
+    @staticmethod
+    @functools.lru_cache(maxsize=128)
+    def _get_model(model_arch: str):
+        module_name, model_cls_name = _MODELS[model_arch]
+        module = importlib.import_module(
+            f"vllm.model_executor.models.{module_name}")
+        return getattr(module, model_cls_name, None)
+
     @staticmethod
     def load_model_cls(model_arch: str) -> Optional[Type[nn.Module]]:
         if model_arch in _OOT_MODELS:
@@ -114,10 +123,7 @@ class ModelRegistry:
                     "Model architecture %s is partially supported by ROCm: %s",
                     model_arch, _ROCM_PARTIALLY_SUPPORTED_MODELS[model_arch])
 
-        module_name, model_cls_name = _MODELS[model_arch]
-        module = importlib.import_module(
-            f"vllm.model_executor.models.{module_name}")
-        return getattr(module, model_cls_name, None)
+        return ModelRegistry._get_model(model_arch)
 
     @staticmethod
     def get_supported_archs() -> List[str]: