Replace time.time() to time.perf_counter() for benchmarking. (#6178)

Signed-off-by: Lifu Huang <lifu.hlf@gmail.com>

benchmark/mmlu/bench_sglang.py

@@ -116,7 +116,7 @@ def main(args):
     backend = select_sglang_backend(args)
 
     # Run
-    tic = time.time()
+    tic = time.perf_counter()
     states = few_shot_mmlu.run_batch(
         arguments,
         temperature=0,
@@ -128,7 +128,7 @@ def main(args):
     preds = [
         s["answer"].strip()[0] if len(s["answer"].strip()) > 0 else "" for s in states
     ]
-    latency = time.time() - tic
+    latency = time.perf_counter() - tic
 
     # Compute accuracy
     cors = [pred == label for pred, label in zip(preds, labels)]