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

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

benchmark/tip_suggestion/bench_sglang.py

@@ -65,11 +65,11 @@ def main(args):
     sgl.set_default_backend(select_sglang_backend(args))
 
     # Run requests
-    tic = time.time()
+    tic = time.perf_counter()
     states = suggest_tips.run_batch(
         arguments, temperature=0, num_threads=args.parallel, progress_bar=True
     )
-    latency = time.time() - tic
+    latency = time.perf_counter() - tic
 
     # Compute accuracy
     print(f"Latency: {latency:.3f}")