diff --git a/src/background_data_service.py b/src/background_data_service.py
index 22989a56..a41aef45 100644
--- a/src/background_data_service.py
+++ b/src/background_data_service.py
@@ -26,6 +26,7 @@ from enum import Enum
 from concurrent.futures import ThreadPoolExecutor
 import pytz
 from src.cache_manager import CacheManager
+from src.common.json_body import response_json
 from src.common.espn_dates import (
     RANGE_RETRY_SECONDS,
     _note_range_rejected,
@@ -389,7 +390,7 @@ class BackgroundDataService:
                         response.raise_for_status()
                 else:
                     response.raise_for_status()
-                    data = response.json()
+                    data = response_json(response)
             
             # Validate data structure
             if not isinstance(data, dict):
diff --git a/src/cache/disk_cache.py b/src/cache/disk_cache.py
index 87c3d7a9..fb776b56 100644
--- a/src/cache/disk_cache.py
+++ b/src/cache/disk_cache.py
@@ -7,6 +7,7 @@ Handles persistent disk-based caching with atomic writes and error recovery.
 import json
 import math
 import os
+import re
 import stat
 import time
 import tempfile
@@ -98,6 +99,40 @@ def _replace_nonfinite(obj: Any) -> Any:
 # deleted. Both halves are covered by test/test_cache_nonfinite_floats.py.
 
 
+#: Enough of a record to hold its header: ``{"timestamp":<float>,"ttl":<n>,``.
+_HEAD_BYTES = 256
+
+#: A record written with its header first (CacheManager.set does). Anything
+#: else -- older files with "data" first, records from other writers -- does not
+#: match and is parsed in full, as before.
+_HEAD_RE = re.compile(
+    rb'\A\s*\{\s*"timestamp"\s*:\s*(-?[0-9][0-9.eE+-]*)\s*'
+    rb'(?:,\s*"ttl"\s*:\s*(-?[0-9][0-9.eE+-]*))?\s*[,}]'
+)
+
+
+def _stale_from_head(head: bytes, max_age: Optional[int], now: float) -> bool:
+    """True when a record's header alone shows it has expired.
+
+    Mirrors the expiry rule in DiskCache.get: a per-entry ttl wins over the
+    caller's max_age, and no limit at all means never stale. False whenever the
+    header cannot be read, so the full parse decides as it always did.
+    """
+    match = _HEAD_RE.match(head)
+    if not match:
+        return False
+    try:
+        timestamp = float(match.group(1))
+        limit = max_age
+        if match.group(2) is not None:
+            ttl = float(match.group(2))
+            if ttl >= 0:
+                limit = ttl
+    except ValueError:
+        return False
+    return limit is not None and (now - timestamp) > limit
+
+
 if orjson is not None:
     # Encoding the cache record dominated the background fetch worker: on a
     # Pi 4, stdlib json.dumps runs ~12ms per MB and holds the GIL for all of
@@ -266,6 +301,14 @@ class DiskCache:
         try:
             with self._lock:
                 with open(cache_path, 'rb') as f:
+                    # Decide staleness from the header before paying for the
+                    # parse. A stale read is the common case for the biggest
+                    # records (a season schedule is re-fetched when its cache
+                    # expires), and parsing 53MB to throw it away held the GIL
+                    # for ~1.8s -- a visible freeze on the panel.
+                    if _stale_from_head(f.read(_HEAD_BYTES), max_age, time.time()):
+                        return None
+                    f.seek(0)
                     record = _loads(f.read())
             
             # Determine record timestamp (prefer embedded, else file mtime)
diff --git a/src/cache_manager.py b/src/cache_manager.py
index 4d80c986..d064a37f 100644
--- a/src/cache_manager.py
+++ b/src/cache_manager.py
@@ -522,8 +522,9 @@ class CacheManager:
     def update_cache(self, data_type: str, data: Dict[str, Any]) -> bool:
         """Update cache with new data."""
         cache_data = {
+            # Header first; see DiskCache's stale check.
+            'timestamp': time.time(),
             'data': data,
-            'timestamp': time.time()
         }
         return self.save_cache(data_type, cache_data)
 
@@ -556,12 +557,15 @@ class CacheManager:
                  from the key and is only a fallback for entries that did not
                  say. Omit it to keep that inferred behaviour.
         """
-        cache_data = {
-            'data': data,
-            'timestamp': time.time()
-        }
+        # timestamp and ttl before data, so they are the first bytes on disk:
+        # DiskCache.get reads them from the head of the file and can call a
+        # record stale without parsing it. That matters for the big ones -- a
+        # whole MLB season is 53MB and ~1.8s of orjson.loads with the GIL held,
+        # paid in full only to learn the record had expired.
+        cache_data: Dict[str, Any] = {'timestamp': time.time()}
         if ttl is not None:
             cache_data['ttl'] = ttl
+        cache_data['data'] = data
         self.save_cache(key, cache_data)
 
     @deprecated("3.7.0")
diff --git a/src/common/espn_dates.py b/src/common/espn_dates.py
index 9be705d1..bda7e86a 100644
--- a/src/common/espn_dates.py
+++ b/src/common/espn_dates.py
@@ -39,6 +39,14 @@ from datetime import date, timedelta
 from functools import partial
 from typing import Any, Dict, List, Optional, Tuple
 
+try:
+    from src.common.json_body import response_json
+except ImportError:
+    # Plugins bundle copies of this module for older cores, which predate
+    # json_body; the stdlib parse is what those cores always used.
+    def response_json(response: Any) -> Any:
+        return response.json()
+
 # Above this, ESPN returns a truncated list instead of an error. See module
 # docstring: 500 is the largest value measured to return complete data.
 ESPN_MAX_LIMIT = 500
@@ -194,7 +202,7 @@ def _fetch_one_chunk(
             timeout=timeout,
         )
         response.raise_for_status()
-        return response.json()
+        return response_json(response)
     except Exception as exc:  # noqa: BLE001 - see docstring
         if logger:
             logger.warning("ESPN chunk %s failed, skipping it: %s", chunk, exc)
@@ -371,4 +379,4 @@ def fetch_espn_scoreboard(
         if data is not None:
             return data
     response.raise_for_status()
-    return response.json()
+    return response_json(response)
diff --git a/src/common/json_body.py b/src/common/json_body.py
new file mode 100644
index 00000000..fb89301d
--- /dev/null
+++ b/src/common/json_body.py
@@ -0,0 +1,29 @@
+"""Parse an HTTP response body as JSON, with orjson when it is installed.
+
+``requests``' ``response.json()`` uses the stdlib parser. For the payloads the
+sports plugins fetch -- a season schedule is tens of MB -- that runs ~1.7x
+slower than orjson on a Pi 4 (3.1s against 1.8s for the 53MB MLB season), and
+both hold the GIL for the whole parse, which freezes the display for as long.
+Nothing else changes: the result is the same Python objects.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+try:
+    import orjson
+except ImportError:  # optional dependency; see docs/SCROLL_PERFORMANCE.md
+    orjson = None
+
+
+def response_json(response: Any) -> Any:
+    """``response.json()``, parsed by orjson when available."""
+    body = getattr(response, "content", None)
+    if orjson is None or not isinstance(body, (bytes, bytearray)):
+        return response.json()
+    try:
+        return orjson.loads(body)
+    except orjson.JSONDecodeError:
+        # Let requests raise its usual error, with its usual message.
+        return response.json()
diff --git a/test/test_cache_stale_header.py b/test/test_cache_stale_header.py
new file mode 100644
index 00000000..026b982d
--- /dev/null
+++ b/test/test_cache_stale_header.py
@@ -0,0 +1,118 @@
+"""A stale cache record is recognised from its header, without parsing it.
+
+The sports plugins cache whole season schedules -- 53MB for MLB, 18MB for NHL.
+When one expired, DiskCache.get parsed all of it (~1.8s of orjson.loads on a
+Pi 4, GIL held, the whole display frozen) only to find the timestamp too old
+and throw the result away. CacheManager.set now writes timestamp and ttl ahead
+of the data, and DiskCache.get reads them from the first bytes of the file.
+"""
+
+import json
+import time
+from types import SimpleNamespace
+
+import pytest
+
+from src.cache import disk_cache as disk_cache_module
+from src.cache.disk_cache import DiskCache, _stale_from_head
+from src.common import json_body
+
+
+@pytest.fixture
+def disk(tmp_path):
+    return DiskCache(cache_dir=str(tmp_path))
+
+
+@pytest.fixture
+def parses(monkeypatch):
+    """Count full parses of cache files."""
+    calls = []
+    real = disk_cache_module._loads
+
+    def counting(raw):
+        calls.append(len(raw))
+        return real(raw)
+
+    monkeypatch.setattr(disk_cache_module, "_loads", counting)
+    return calls
+
+
+def _header_first(age=0.0, ttl=None, events=100):
+    record = {"timestamp": time.time() - age}
+    if ttl is not None:
+        record["ttl"] = ttl
+    record["data"] = {"events": [{"id": n, "name": "x" * 50} for n in range(events)]}
+    return record
+
+
+def test_cache_manager_writes_the_header_first(monkeypatch):
+    from src.cache_manager import CacheManager
+    written = {}
+    manager = CacheManager.__new__(CacheManager)
+    monkeypatch.setattr(manager, "save_cache",
+                        lambda key, record: written.update({key: record}),
+                        raising=False)
+    CacheManager.set(manager, "k", {"events": []}, ttl=60)
+    assert list(written["k"]) == ["timestamp", "ttl", "data"]
+    CacheManager.set(manager, "k", {"events": []})
+    assert list(written["k"]) == ["timestamp", "data"]
+
+
+def test_a_stale_record_is_not_parsed(disk, parses):
+    disk.set("season", _header_first(age=600))
+    assert disk.get("season", max_age=300) is None
+    assert parses == []
+
+
+def test_a_fresh_record_is_parsed_and_returned(disk, parses):
+    disk.set("season", _header_first(age=10))
+    record = disk.get("season", max_age=300)
+    assert record["data"]["events"][0]["id"] == 0
+    assert len(parses) == 1
+
+
+def test_the_entry_ttl_wins_over_max_age(disk, parses):
+    disk.set("long", _header_first(age=600, ttl=3600))
+    assert disk.get("long", max_age=300) is not None     # ttl says fresh
+    disk.set("short", _header_first(age=60, ttl=30))
+    parses.clear()
+    assert disk.get("short", max_age=300) is None        # ttl says stale
+    assert parses == []
+
+
+def test_no_limit_means_never_stale(disk):
+    disk.set("forever", _header_first(age=10 ** 7))
+    assert disk.get("forever", max_age=None) is not None
+
+
+def test_older_files_with_data_first_still_work(disk, parses):
+    # Records written before the header moved: parsed in full, as before.
+    disk.set("legacy_fresh", {"data": {"v": 1}, "timestamp": time.time()})
+    disk.set("legacy_stale", {"data": {"v": 1}, "timestamp": time.time() - 600})
+    assert disk.get("legacy_fresh", max_age=300)["data"] == {"v": 1}
+    assert disk.get("legacy_stale", max_age=300) is None
+    assert len(parses) == 2
+
+
+@pytest.mark.parametrize("head, stale", [
+    (b'{"timestamp":100.0,"data":{}}', True),
+    (b'{"timestamp": 100.0, "ttl": 1000, "data": {}}', False),   # stdlib spacing
+    (b'{"timestamp":1e2,"ttl":5,"data":1}', True),
+    (b'{"timestamp":100.0}', True),
+    (b'{"data":{},"timestamp":100.0}', False),                  # unknown layout
+    (b'{"timestamp":"100.0","data":{}}', False),                # string: parse it
+    (b'', False),
+])
+def test_reading_the_header(head, stale):
+    assert _stale_from_head(head, 300, now=1000.0) is stale
+
+
+def test_response_json_prefers_orjson_and_falls_back():
+    payload = {"events": [1, 2, 3]}
+    response = SimpleNamespace(content=json.dumps(payload).encode(),
+                               json=lambda: pytest.fail("used the slow path"))
+    if json_body.orjson is None:
+        pytest.skip("orjson not installed")
+    assert json_body.response_json(response) == payload
+    # A response object without bytes content (a test double) still works.
+    assert json_body.response_json(SimpleNamespace(json=lambda: payload)) == payload