diff --git a/activitysim/cli/main.py b/activitysim/cli/main.py
index 8ac2666b20..08250f382f 100644
--- a/activitysim/cli/main.py
+++ b/activitysim/cli/main.py
@@ -44,8 +44,18 @@ def prog():
 
 
 def main():
-    # set all these before we import numpy or any other math library
+    prevent_multithreading = False
     if len(sys.argv) > 1 and sys.argv[1] == "benchmark":
+        # We cannot use multiple threads for benchmarking, as it can foil timing
+        prevent_multithreading = True
+    if "--fast" not in sys.argv:
+        # If we are not in fast mode, we want to prevent multithreading to avoid
+        # issues with some libraries crashing. Fast mode is not stable enough
+        # at scale to use by default, but can be used for testing and development.
+        prevent_multithreading = True
+
+    # set all these before we import numpy or any other math library
+    if prevent_multithreading:
         os.environ["MKL_NUM_THREADS"] = "1"
         os.environ["OMP_NUM_THREADS"] = "1"
         os.environ["OPENBLAS_NUM_THREADS"] = "1"
diff --git a/activitysim/core/mp_tasks.py b/activitysim/core/mp_tasks.py
index f54e2f8d2f..c8507138f4 100644
--- a/activitysim/core/mp_tasks.py
+++ b/activitysim/core/mp_tasks.py
@@ -19,6 +19,7 @@
 
 from activitysim.core import config, mem, tracing, util, workflow
 from activitysim.core.configuration import FileSystem, Settings
+from activitysim.core.exceptions import *
 from activitysim.core.run_id import RunId
 from activitysim.core.workflow.checkpoint import (
     CHECKPOINT_NAME,
@@ -27,7 +28,6 @@
     NON_TABLE_COLUMNS,
     ParquetStore,
 )
-from activitysim.core.exceptions import *
 
 logger = logging.getLogger(__name__)
 
@@ -257,6 +257,21 @@ def exception(state: workflow.State, msg, write_to_log_file=True):
         logger.log(logging.ERROR, f"\n---\n{traceback.format_exc()}---\n")
 
 
+def log_environment_info(state: workflow.State):
+    """log environment info for debugging purposes."""
+    if os.environ.get("ASIM_LOG_ENVIRON", False):
+        process_name = multiprocessing.current_process().name
+        environ_summary = f"OS.ENVIRON in process {process_name}:"
+        for k, v in os.environ.items():
+            environ_summary += f"\n--- {k}: {v}"
+        info(state, environ_summary)
+    else:
+        info(
+            state,
+            "ASIM_LOG_ENVIRON not set, skipping logging of environment variables. Set ASIM_LOG_ENVIRON=1 to log environment variables.",
+        )
+
+
 """
 ### child process methods (called within sub process)
 """
@@ -1097,6 +1112,7 @@ def mp_run_simulation(
         state,
         f"mp_run_simulation {step_info['name']} locutor={state.get_injectable('locutor', False)} ",
     )
+    log_environment_info(state)
 
     try:
         if step_info["num_processes"] > 1:
@@ -1417,6 +1433,7 @@ def check_proc_status(state: workflow.State):
     completed = set(previously_completed)
     failed = set([])  # so we can log process failure first time it happens
     drop_breadcrumb(state, step_name, "completed", list(completed))
+    log_environment_info(state)
 
     for i, process_name in enumerate(process_names):
         q = multiprocessing.Queue()
diff --git a/other_resources/scripts/clear_sharrow_cache.py b/other_resources/scripts/clear_sharrow_cache.py
new file mode 100644
index 0000000000..44a805792a
--- /dev/null
+++ b/other_resources/scripts/clear_sharrow_cache.py
@@ -0,0 +1,56 @@
+#!/usr/bin/env -S uv run --script --no-project
+#
+# /// script
+# requires-python = ">=3.10,<3.12"
+# dependencies = [
+#   "platformdirs",
+# ]
+# ///
+
+from __future__ import annotations
+
+import shutil
+from datetime import datetime
+from pathlib import Path
+
+import platformdirs
+
+
+def clear_sharrow_cache(archive: bool = True):
+    """Disable all files in the sharrow cache directory.
+
+    Parameters
+    ----------
+    archive : bool, optional
+        If True, move the files to an 'archive' subdirectory instead of deleting them,
+        by default True.
+    """
+    main_dir = Path(platformdirs.user_cache_dir(appname="ActivitySim"))
+    print(f"Scanning ActivitySim cache directory for sharrow files: {main_dir}")
+    sharrow_cache_dirs = main_dir.glob("sharrow-*-numba-*")
+    timestamp = datetime.now().strftime("%Y%m%d-%H%M%S")
+
+    # define the archive path if archiving is enabled
+    if archive:
+        archive_path = Path(
+            platformdirs.user_cache_dir(appname="ActivitySim")
+        ).joinpath(f"archive-{timestamp}")
+    else:
+        archive_path = None
+
+    for sharrow_cache_dir in sharrow_cache_dirs:
+        if sharrow_cache_dir.is_dir():
+            print(f"Clearing sharrow cache directory: {sharrow_cache_dir}")
+            if archive:
+                archive_path.mkdir(parents=True, exist_ok=True)
+                shutil.move(
+                    str(sharrow_cache_dir), str(archive_path / sharrow_cache_dir.name)
+                )
+            else:
+                shutil.rmtree(str(sharrow_cache_dir))
+    else:
+        print("No sharrow cache directories found.")
+
+
+if __name__ == "__main__":
+    clear_sharrow_cache(archive=True)