diff --git a/activitysim/core/chunk.py b/activitysim/core/chunk.py
index 252b780e19..4ae26873c6 100644
--- a/activitysim/core/chunk.py
+++ b/activitysim/core/chunk.py
@@ -74,7 +74,8 @@
 MODE_RETRAIN = 'training'
 MODE_ADAPTIVE = 'adaptive'
 MODE_PRODUCTION = 'production'
-TRAINING_MODES = [MODE_RETRAIN, MODE_ADAPTIVE, MODE_PRODUCTION]
+MODE_CHUNKLESS = 'disabled'
+TRAINING_MODES = [MODE_RETRAIN, MODE_ADAPTIVE, MODE_PRODUCTION, MODE_CHUNKLESS]
 
 #
 # low level
@@ -135,7 +136,9 @@ def chunk_metric():
 def chunk_training_mode():
     training_mode = \
         SETTINGS.setdefault('chunk_training_mode', config.setting('chunk_training_mode', MODE_ADAPTIVE))
-    assert training_mode in TRAINING_MODES, f"chunk_training_mode '{training_mode} not one of: {TRAINING_MODES}"
+    if not training_mode:
+        training_mode = MODE_CHUNKLESS
+    assert training_mode in TRAINING_MODES, f"chunk_training_mode '{training_mode}' not one of: {TRAINING_MODES}"
     return training_mode
 
 
@@ -223,8 +226,9 @@ def consolidate_logs():
     if not glob_files:
         return
 
-    assert chunk_training_mode() != MODE_PRODUCTION, \
-        f"shouldn't be any chunk log files when chunk_training_mode is {MODE_PRODUCTION}"
+    assert chunk_training_mode() not in (MODE_PRODUCTION, MODE_CHUNKLESS), \
+        f"shouldn't be any chunk log files when chunk_training_mode" \
+        f" is {MODE_PRODUCTION} or {MODE_CHUNKLESS}"
 
     #
     # OMNIBUS_LOG_FILE
@@ -331,6 +335,9 @@ def load_cached_history(self):
         else:
             self.have_cached_history = False
 
+            if chunk_training_mode() == MODE_CHUNKLESS:
+                return
+
             if chunk_training_mode() == MODE_PRODUCTION:
                 # raise RuntimeError(f"chunk_training_mode is {MODE_PRODUCTION} but no chunk_cache: {chunk_cache_path}")
 
@@ -379,7 +386,7 @@ def cached_row_size(self, chunk_tag):
 
     def write_history(self, history, chunk_tag):
 
-        assert chunk_training_mode() != MODE_PRODUCTION
+        assert chunk_training_mode() not in (MODE_PRODUCTION, MODE_CHUNKLESS)
 
         history_df = pd.DataFrame.from_dict(history)
 
@@ -418,7 +425,7 @@ def __init__(self, trace_label, chunk_size, baseline_rss, baseline_uss, headroom
 
     def audit(self, msg, bytes=0, rss=0, uss=0, from_rss_monitor=False):
 
-        assert chunk_training_mode() != MODE_PRODUCTION
+        assert chunk_training_mode() not in (MODE_PRODUCTION, MODE_CHUNKLESS)
 
         MAX_OVERDRAFT = 0.2
 
@@ -483,7 +490,7 @@ def size_it(df):
                 assert False
             return elements, bytes
 
-        assert chunk_training_mode() != MODE_PRODUCTION
+        assert chunk_training_mode() not in (MODE_PRODUCTION, MODE_CHUNKLESS)
 
         if df is None:
             elements, bytes = (0, 0)
@@ -511,7 +518,7 @@ def size_it(df):
 
     def check_local_hwm(self, hwm_trace_label, rss, uss, total_bytes):
 
-        assert chunk_training_mode() != MODE_PRODUCTION
+        assert chunk_training_mode() not in (MODE_PRODUCTION, MODE_CHUNKLESS)
 
         from_rss_monitor = total_bytes is None
 
@@ -563,13 +570,18 @@ def get_hwm_bytes(self):
 
 def log_rss(trace_label, force=False):
 
+    if chunk_training_mode() == MODE_CHUNKLESS:
+        # no memory tracing at all in chunkless mode
+        return
+
     assert len(CHUNK_LEDGERS) > 0, f"log_rss called without current chunker."
 
     hwm_trace_label = f"{trace_label}.log_rss"
 
     if chunk_training_mode() == MODE_PRODUCTION:
-        trace_ticks = 0 if force else mem.MEM_TRACE_TICK_LEN
-        mem.trace_memory_info(hwm_trace_label, trace_ticks=trace_ticks)
+        # FIXME - this trace_memory_info call slows things down a lot so it is turned off for now
+        # trace_ticks = 0 if force else mem.MEM_TRACE_TICK_LEN
+        # mem.trace_memory_info(hwm_trace_label, trace_ticks=trace_ticks)
         return
 
     rss, uss = mem.trace_memory_info(hwm_trace_label)
@@ -582,11 +594,11 @@ def log_rss(trace_label, force=False):
 
 def log_df(trace_label, table_name, df):
 
-    assert len(CHUNK_LEDGERS) > 0, f"log_df called without current chunker."
-
-    if chunk_training_mode() == MODE_PRODUCTION:
+    if chunk_training_mode() in (MODE_PRODUCTION, MODE_CHUNKLESS):
         return
 
+    assert len(CHUNK_LEDGERS) > 0, f"log_df called without current chunker."
+
     op = 'del' if df is None else 'add'
     hwm_trace_label = f"{trace_label}.{op}.{table_name}"
 
@@ -624,19 +636,27 @@ class ChunkSizer(object):
     def __init__(self, chunk_tag, trace_label, num_choosers=0, chunk_size=0):
 
         self.depth = len(CHUNK_SIZERS) + 1
-        self.rss, self.uss = mem.get_rss(force_garbage_collect=True, uss=True)
 
-        if self.depth > 1:
-            # nested chunkers should be unchunked
-            assert chunk_size == 0
+        if chunk_training_mode() != MODE_CHUNKLESS:
+            if chunk_metric() == USS:
+                self.rss, self.uss = mem.get_rss(force_garbage_collect=True, uss=True)
+            else:
+                self.rss, _ = mem.get_rss(force_garbage_collect=True, uss=False)
+                self.uss = 0
 
-            # if we are in a nested call, then we must be in the scope of active Ledger
-            # so any rss accumulated so far should be attributed to the parent active ledger
-            assert len(CHUNK_SIZERS) == len(CHUNK_LEDGERS)
-            parent = CHUNK_SIZERS[-1]
-            assert parent.chunk_ledger is not None
+            if self.depth > 1:
+                # nested chunkers should be unchunked
+                assert chunk_size == 0
 
-            log_rss(trace_label)  # give parent a complementary log_rss reading entering sub context
+                # if we are in a nested call, then we must be in the scope of active Ledger
+                # so any rss accumulated so far should be attributed to the parent active ledger
+                assert len(CHUNK_SIZERS) == len(CHUNK_LEDGERS)
+                parent = CHUNK_SIZERS[-1]
+                assert parent.chunk_ledger is not None
+
+                log_rss(trace_label)  # give parent a complementary log_rss reading entering sub context
+        else:
+            self.rss, self.uss = 0, 0
 
         self.chunk_tag = chunk_tag
         self.trace_label = trace_label
@@ -679,7 +699,8 @@ def __init__(self, chunk_tag, trace_label, num_choosers=0, chunk_size=0):
 
     def close(self):
 
-        if ((self.depth == 1) or WRITE_SUBCHUNK_HISTORY) and (chunk_training_mode() != MODE_PRODUCTION):
+        if ((self.depth == 1) or WRITE_SUBCHUNK_HISTORY) and \
+                (chunk_training_mode() not in (MODE_PRODUCTION, MODE_CHUNKLESS)):
             _HISTORIAN.write_history(self.history, self.chunk_tag)
 
         _chunk_sizer = CHUNK_SIZERS.pop()
@@ -755,7 +776,12 @@ def adaptive_rows_per_chunk(self, i):
 
         prev_rss = self.rss
         prev_uss = self.uss
-        self.rss, self.uss = mem.get_rss(force_garbage_collect=True, uss=True)
+
+        if chunk_metric() == USS:
+            self.rss, self.uss = mem.get_rss(force_garbage_collect=True, uss=True)
+        else:
+            self.rss, _ = mem.get_rss(force_garbage_collect=True, uss=False)
+            self.uss = 0
 
         self.headroom = self.available_headroom(self.uss if chunk_metric() == USS else self.rss)
 
@@ -826,7 +852,7 @@ def adaptive_rows_per_chunk(self, i):
 
         # input()
 
-        if chunk_training_mode() != MODE_PRODUCTION:
+        if chunk_training_mode() not in (MODE_PRODUCTION, MODE_CHUNKLESS):
             self.cum_rows += self.rows_per_chunk
 
         return self.rows_per_chunk, estimated_number_of_chunks
@@ -834,6 +860,11 @@ def adaptive_rows_per_chunk(self, i):
     @contextmanager
     def ledger(self):
 
+        # don't do anything in chunkless mode
+        if chunk_training_mode() == MODE_CHUNKLESS:
+            yield
+            return
+
         mem_monitor = None
 
         # nested chunkers should be unchunked
@@ -899,7 +930,8 @@ def chunk_log(trace_label, chunk_tag=None, base=False):
 
         yield
 
-        chunk_sizer.adaptive_rows_per_chunk(1)
+        if chunk_training_mode() != MODE_CHUNKLESS:
+            chunk_sizer.adaptive_rows_per_chunk(1)
 
     chunk_sizer.close()
 
@@ -940,7 +972,8 @@ def adaptive_chunked_choosers(choosers, chunk_size, trace_label, chunk_tag=None)
 
             offset += rows_per_chunk
 
-            rows_per_chunk, estimated_number_of_chunks = chunk_sizer.adaptive_rows_per_chunk(i)
+            if chunk_training_mode() != MODE_CHUNKLESS:
+                rows_per_chunk, estimated_number_of_chunks = chunk_sizer.adaptive_rows_per_chunk(i)
 
     chunk_sizer.close()
 
@@ -1034,7 +1067,8 @@ def adaptive_chunked_choosers_and_alts(choosers, alternatives, chunk_size, trace
             offset += rows_per_chunk
             alt_offset = alt_end
 
-            rows_per_chunk, estimated_number_of_chunks = chunk_sizer.adaptive_rows_per_chunk(i)
+            if chunk_training_mode() != MODE_CHUNKLESS:
+                rows_per_chunk, estimated_number_of_chunks = chunk_sizer.adaptive_rows_per_chunk(i)
 
     chunk_sizer.close()
 
@@ -1074,6 +1108,7 @@ def adaptive_chunked_choosers_by_chunk_id(choosers, chunk_size, trace_label, chu
 
             offset += rows_per_chunk
 
-            rows_per_chunk, estimated_number_of_chunks = chunk_sizer.adaptive_rows_per_chunk(i)
+            if chunk_training_mode() != MODE_CHUNKLESS:
+                rows_per_chunk, estimated_number_of_chunks = chunk_sizer.adaptive_rows_per_chunk(i)
 
     chunk_sizer.close()
diff --git a/activitysim/core/config.py b/activitysim/core/config.py
index 6d3dc89b49..b85a02e81a 100644
--- a/activitysim/core/config.py
+++ b/activitysim/core/config.py
@@ -553,6 +553,12 @@ def filter_warnings():
     warnings.filterwarnings('ignore', category=DeprecationWarning, module='tables',
                             message='`np.object` is a deprecated alias')
 
+    # beginning pandas version 1.3, various places emit a PerformanceWarning that is
+    # caught in the "strict" filter above, but which are currently unavoidable for complex models.
+    # These warning are left as warnings as an invitation for future enhancement.
+    from pandas.errors import PerformanceWarning
+    warnings.filterwarnings('default', category=PerformanceWarning)
+
 
 def handle_standard_args(parser=None):
 
diff --git a/activitysim/core/simulate.py b/activitysim/core/simulate.py
index 937e73c4e7..5d627f1ed6 100644
--- a/activitysim/core/simulate.py
+++ b/activitysim/core/simulate.py
@@ -229,7 +229,10 @@ def read_model_coefficient_template(model_settings):
     # this makes for a more legible template than repeating the identical coefficient name in each column
 
     # replace missing cell values with coefficient_name from index
-    template = template.where(~template.isnull(), template.index)
+    template = template.where(
+        ~template.isnull(),
+        np.broadcast_to(template.index.values[:, None], template.shape),
+    )
 
     if template.index.duplicated().any():
         dupes = template[template.index.duplicated(keep=False)].sort_index()
diff --git a/activitysim/examples/example_mtc/test/configs_chunkless/network_los.yaml b/activitysim/examples/example_mtc/test/configs_chunkless/network_los.yaml
new file mode 100644
index 0000000000..1c4cd79daf
--- /dev/null
+++ b/activitysim/examples/example_mtc/test/configs_chunkless/network_los.yaml
@@ -0,0 +1,6 @@
+inherit_settings: True
+
+# read cached skims (using numpy memmap) from output directory (memmap is faster than omx )
+read_skim_cache: False
+# write memmapped cached skims to output directory after reading from omx, for use in subsequent runs
+write_skim_cache: False
diff --git a/activitysim/examples/example_mtc/test/configs_chunkless/settings.yaml b/activitysim/examples/example_mtc/test/configs_chunkless/settings.yaml
new file mode 100644
index 0000000000..3e670aca94
--- /dev/null
+++ b/activitysim/examples/example_mtc/test/configs_chunkless/settings.yaml
@@ -0,0 +1,26 @@
+inherit_settings: True
+
+# treat warnings as errors
+strict: True
+
+# number of households to simulate
+households_sample_size:  10
+chunk_size: 0
+chunk_training_mode: disabled
+
+# - shadow pricing global switches
+use_shadow_pricing: False
+
+# turn writing of sample_tables on and off for all models
+# (if True, tables will be written if DEST_CHOICE_SAMPLE_TABLE_NAME is specified in individual model settings)
+want_dest_choice_sample_tables: False
+
+cleanup_pipeline_after_run: True
+
+output_tables:
+  h5_store: False
+  action: include
+  prefix: final_
+  sort: True
+  tables:
+    - trips
diff --git a/activitysim/examples/example_mtc/test/test_mtc.py b/activitysim/examples/example_mtc/test/test_mtc.py
index 8eccb2c3ea..a81c439cbd 100644
--- a/activitysim/examples/example_mtc/test/test_mtc.py
+++ b/activitysim/examples/example_mtc/test/test_mtc.py
@@ -15,7 +15,7 @@ def teardown_function(func):
     inject.reinject_decorated_tables()
 
 
-def run_test_mtc(multiprocess=False):
+def run_test_mtc(multiprocess=False, chunkless=False):
 
     def example_path(dirname):
         resource = os.path.join('examples', 'example_mtc', dirname)
@@ -38,6 +38,9 @@ def regress():
     if multiprocess:
         run_args = ['-c', test_path('configs_mp'), '-c', example_path('configs_mp'), '-c', example_path('configs'),
                     '-d', example_path('data'), '-o', test_path('output')]
+    elif chunkless:
+        run_args = ['-c', test_path('configs_chunkless'), '-c', example_path('configs'),
+                    '-d', example_path('data'), '-o', test_path('output')]
     else:
         run_args = ['-c', test_path('configs'), '-c', example_path('configs'),
                     '-d', example_path('data'), '-o', test_path('output')]
@@ -51,6 +54,10 @@ def test_mtc():
     run_test_mtc(multiprocess=False)
 
 
+def test_mtc_chunkless():
+    run_test_mtc(multiprocess=False, chunkless=True)
+
+
 def test_mtc_mp():
     run_test_mtc(multiprocess=True)
 
@@ -59,3 +66,4 @@ def test_mtc_mp():
 
     run_test_mtc(multiprocess=False)
     run_test_mtc(multiprocess=True)
+    run_test_mtc(multiprocess=False, chunkless=True)