diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1963a4e7..66bf5656 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## 1.6.3
+
+### Enhancement
+- Make ONNX Runtime memory arena configurable via `ONNX_DISABLE_MEMORY_ARENA` env var (default: enabled). Set to `1` to trade ~15% inference latency for ~209 MB idle memory savings per session.
+
 ## 1.6.2
 
 ### Enhancement
@@ -17,6 +22,7 @@
 
 ### Enhancement
 - Lazy page rendering in `convert_pdf_to_image` to reduce peak memory from O(N pages) to O(1 page)
+>>>>>>> upstream/main
 
 ## 1.5.4
 
diff --git a/unstructured_inference/__version__.py b/unstructured_inference/__version__.py
index 4e4d3296..f005954b 100644
--- a/unstructured_inference/__version__.py
+++ b/unstructured_inference/__version__.py
@@ -1 +1 @@
-__version__ = "1.6.2"  # pragma: no cover
+__version__ = "1.6.3"  # pragma: no cover
diff --git a/unstructured_inference/models/detectron2onnx.py b/unstructured_inference/models/detectron2onnx.py
index 79cd0a1a..e47dccc1 100644
--- a/unstructured_inference/models/detectron2onnx.py
+++ b/unstructured_inference/models/detectron2onnx.py
@@ -21,6 +21,11 @@
     download_if_needed_and_get_local_path,
 )
 
+_ONNX_DISABLE_MEMORY_ARENA = os.environ.get("ONNX_DISABLE_MEMORY_ARENA", "").strip().lower() in (
+    "1",
+    "true",
+)
+
 onnxruntime.set_default_logger_severity(logger_onnx.getEffectiveLevel())
 
 DEFAULT_LABEL_MAP: Final[Dict[int, str]] = {
@@ -115,8 +120,14 @@ def initialize(
         ]
         providers = [provider for provider in ordered_providers if provider in available_providers]
 
+        sess_options = onnxruntime.SessionOptions()
+        if _ONNX_DISABLE_MEMORY_ARENA:
+            sess_options.enable_mem_pattern = False
+            sess_options.enable_cpu_mem_arena = False
+
         self.model = onnxruntime.InferenceSession(
             model_path,
+            sess_options=sess_options,
             providers=providers,
         )
         self.model_path = model_path
diff --git a/unstructured_inference/models/yolox.py b/unstructured_inference/models/yolox.py
index cdf1f405..c3b466d3 100644
--- a/unstructured_inference/models/yolox.py
+++ b/unstructured_inference/models/yolox.py
@@ -3,6 +3,8 @@
 # https://github.com/Megvii-BaseDetection/YOLOX/blob/237e943ac64aa32eb32f875faa93ebb18512d41d/yolox/data/data_augment.py
 # https://github.com/Megvii-BaseDetection/YOLOX/blob/ac379df3c97d1835ebd319afad0c031c36d03f36/yolox/utils/demo_utils.py
 
+import os
+
 import cv2
 import numpy as np
 import onnxruntime
@@ -20,6 +22,11 @@
     download_if_needed_and_get_local_path,
 )
 
+_ONNX_DISABLE_MEMORY_ARENA = os.environ.get("ONNX_DISABLE_MEMORY_ARENA", "").strip().lower() in (
+    "1",
+    "true",
+)
+
 YOLOX_LABEL_MAP = {
     0: ElementType.CAPTION,
     1: ElementType.FOOTNOTE,
@@ -80,8 +87,14 @@ def initialize(self, model_path: str, label_map: dict):
         ]
         providers = [provider for provider in ordered_providers if provider in available_providers]
 
+        sess_options = onnxruntime.SessionOptions()
+        if _ONNX_DISABLE_MEMORY_ARENA:
+            sess_options.enable_mem_pattern = False
+            sess_options.enable_cpu_mem_arena = False
+
         self.model = onnxruntime.InferenceSession(
             model_path,
+            sess_options=sess_options,
             providers=providers,
         )