diff --git a/vllm/model_executor/layers/sampler.py b/vllm/model_executor/layers/sampler.py
index 5c376797a054f..121458f8156a1 100644
--- a/vllm/model_executor/layers/sampler.py
+++ b/vllm/model_executor/layers/sampler.py
@@ -220,7 +220,7 @@ def _apply_min_tokens_penalty(
             seqs_to_penalize: List[int] = []
             for j, seq_id in enumerate(seq_ids):
                 seq_data = seq_group.seq_data[seq_id]
-                if len(seq_data.output_token_ids) < min_tokens:
+                if len(seq_data.output_token_ids_array) < min_tokens:
                     seqs_to_penalize.append(j)
 
             if seqs_to_penalize:
diff --git a/vllm/model_executor/sampling_metadata.py b/vllm/model_executor/sampling_metadata.py
index 390b5d173ebcd..27b37a9d53470 100644
--- a/vllm/model_executor/sampling_metadata.py
+++ b/vllm/model_executor/sampling_metadata.py
@@ -1,4 +1,5 @@
 import random
+from array import array
 from dataclasses import dataclass
 from typing import Dict, List, Optional, Tuple
 
@@ -329,8 +330,8 @@ def from_sampling_metadata(
             user-defined seed for each sequence.
         extra_entropy: extra entropy to use when generating seeds.
         """
-        prompt_tokens: List[List[int]] = []
-        output_tokens: List[List[int]] = []
+        prompt_tokens: List[array] = []
+        output_tokens: List[array] = []
         top_ks: List[int] = []
         temperatures: List[float] = []
         top_ps: List[float] = []
@@ -432,13 +433,15 @@ def from_sampling_metadata(
                 if (seq_group.is_prompt
                         and sampling_params.prompt_logprobs is not None):
                     prefill_len = len(seq_group.prompt_logprob_indices)
-                    prompt_tokens.extend([] for _ in range(prefill_len))
-                    output_tokens.extend([] for _ in range(prefill_len))
+                    prompt_tokens.extend(
+                        array('l') for _ in range(prefill_len))
+                    output_tokens.extend(
+                        array('l') for _ in range(prefill_len))
                 if seq_group.do_sample:
                     for seq_id in seq_ids:
                         seq_data = seq_group.seq_data[seq_id]
-                        prompt_tokens.append(list(seq_data.prompt_token_ids))
-                        output_tokens.append(list(seq_data.output_token_ids))
+                        prompt_tokens.append(seq_data.prompt_token_ids_array)
+                        output_tokens.append(seq_data.output_token_ids_array)
 
         sampling_tensors = SamplingTensors.from_lists(
             temperatures, top_ps, top_ks, min_ps, presence_penalties,
@@ -454,9 +457,9 @@ def from_lists(cls, temperatures: List[float], top_ps: List[float],
                    frequency_penalties: List[float],
                    repetition_penalties: List[float],
                    sampling_seeds: List[int], sample_indices: List[int],
-                   prompt_tokens: List[List[int]],
-                   output_tokens: List[List[int]], vocab_size: int,
-                   extra_seeds_to_generate: int, device: torch.device,
+                   prompt_tokens: List[array], output_tokens: List[array],
+                   vocab_size: int, extra_seeds_to_generate: int,
+                   device: torch.device,
                    dtype: torch.dtype) -> "SamplingTensors":
         # Note that the performance will be very bad without
         # pinned memory.
diff --git a/vllm/sequence.py b/vllm/sequence.py
index 0cd4c7e71d78d..72821ecea0f47 100644
--- a/vllm/sequence.py
+++ b/vllm/sequence.py
@@ -3,6 +3,7 @@
 import enum
 import math
 from abc import ABC, abstractmethod
+from array import array
 from collections import defaultdict
 from dataclasses import dataclass, field
 from typing import (TYPE_CHECKING, Dict, List, Mapping, Optional, Set, Tuple,
@@ -119,10 +120,10 @@ def __init__(
         prompt_token_ids: List[int],
         output_token_ids: Optional[List[int]] = None,
     ) -> None:
-        self._prompt_token_ids: List[int] = list(prompt_token_ids)
+        self._prompt_token_ids = array('l', prompt_token_ids)
         self._prompt_token_ids_tuple: Tuple[int, ...] = tuple(prompt_token_ids)
-        self._output_token_ids: List[int] = (
-            list(output_token_ids) if output_token_ids is not None else [])
+        self._output_token_ids = array(
+            'l', output_token_ids if output_token_ids is not None else [])
 
         self.cumulative_logprob = 0.0
         # The number of tokens that are computed (that run against the model).
@@ -132,8 +133,8 @@ def __init__(
         self._update_cached_all_tokens()
 
     def _update_cached_all_tokens(self):
-        self._cached_all_token_ids: List[int] = (self._prompt_token_ids +
-                                                 self._output_token_ids)
+        self._cached_all_token_ids: List[int] = list(self._prompt_token_ids +
+                                                     self._output_token_ids)
 
     @property
     def prompt_token_ids(self) -> Tuple[int, ...]:
@@ -141,19 +142,27 @@ def prompt_token_ids(self) -> Tuple[int, ...]:
 
     @prompt_token_ids.setter
     def prompt_token_ids(self, new_prompt_token_ids) -> None:
-        self._prompt_token_ids = list(new_prompt_token_ids)
+        self._prompt_token_ids = array('l', new_prompt_token_ids)
         self._prompt_token_ids_tuple = tuple(new_prompt_token_ids)
         self._update_cached_all_tokens()
 
+    @property
+    def prompt_token_ids_array(self) -> array:
+        return self._prompt_token_ids
+
     @property
     def output_token_ids(self) -> Tuple[int, ...]:
         return tuple(self._output_token_ids)
 
     @output_token_ids.setter
     def output_token_ids(self, new_output_token_ids) -> None:
-        self._output_token_ids = list(new_output_token_ids)
+        self._output_token_ids = array('l', new_output_token_ids)
         self._update_cached_all_tokens()
 
+    @property
+    def output_token_ids_array(self) -> array:
+        return self._output_token_ids
+
     def append_token_id(self, token_id: int, logprob: float) -> None:
         self._output_token_ids.append(token_id)
         self._cached_all_token_ids.append(token_id)