diff --git a/mrmustard/training/optimizer.py b/mrmustard/training/optimizer.py
index c5a9bffb9..dec84e797 100644
--- a/mrmustard/training/optimizer.py
+++ b/mrmustard/training/optimizer.py
@@ -18,7 +18,7 @@
 
 from itertools import chain, groupby
 from typing import List, Callable, Sequence, Union, Mapping, Dict
-from mrmustard import math
+from mrmustard import math, settings
 from mrmustard.math.parameters import Constant, Variable
 from mrmustard.training.callbacks import Callback
 from mrmustard.training.progress_bar import ProgressBar
@@ -98,35 +98,58 @@ def minimize(
     def _minimize(self, cost_fn, by_optimizing, max_steps, callbacks):
         # finding out which parameters are trainable from the ops
         trainable_params = self._get_trainable_params(by_optimizing)
+        if settings.PROGRESSBAR:
+            bar = ProgressBar(max_steps)
+            with bar:
+                self._optimization_loop(cost_fn, trainable_params, max_steps, callbacks, bar)
+        else:
+            self._optimization_loop(cost_fn, trainable_params, max_steps, callbacks)
+
+    def _optimization_loop(
+        self, cost_fn, trainable_params, max_steps, callbacks, progress_bar=None
+    ):
+        """Internal method that performs the main optimization loop.
+
+        Args:
+            cost_fn (Callable): The cost function to minimize
+            trainable_params (dict): Dictionary of trainable parameters
+            max_steps (int): Maximum number of optimization steps
+            callbacks (dict): Dictionary of callback functions to execute during optimization
+            progress_bar (ProgressBar, optional): Progress bar instance for displaying optimization progress.
+                If None, no progress will be displayed. Defaults to None.
+
+        Note:
+            This method maintains internal state in self.opt_history and self.callback_history,
+            tracking the optimization progress and callback results respectively.
+        """
         cost_fn_modified = False
         orig_cost_fn = cost_fn
 
-        bar = ProgressBar(max_steps)
-        with bar:
-            while not self.should_stop(max_steps):
-                cost, grads = self.compute_loss_and_gradients(cost_fn, trainable_params.values())
+        while not self.should_stop(max_steps):
+            cost, grads = self.compute_loss_and_gradients(cost_fn, trainable_params.values())
 
-                trainables = {tag: (x, dx) for (tag, x), dx in zip(trainable_params.items(), grads)}
+            trainables = {tag: (x, dx) for (tag, x), dx in zip(trainable_params.items(), grads)}
 
-                if cost_fn_modified:
-                    self.callback_history["orig_cost"].append(orig_cost_fn())
+            if cost_fn_modified:
+                self.callback_history["orig_cost"].append(orig_cost_fn())
 
-                new_cost_fn, new_grads = self._run_callbacks(
-                    callbacks=callbacks,
-                    cost_fn=cost_fn,
-                    cost=cost,
-                    trainables=trainables,
-                )
+            new_cost_fn, new_grads = self._run_callbacks(
+                callbacks=callbacks,
+                cost_fn=cost_fn,
+                cost=cost,
+                trainables=trainables,
+            )
 
-                self.apply_gradients(trainable_params.values(), new_grads or grads)
-                self.opt_history.append(cost)
-                bar.step(math.asnumpy(cost))
+            self.apply_gradients(trainable_params.values(), new_grads or grads)
+            self.opt_history.append(cost)
+            if progress_bar is not None:
+                progress_bar.step(math.asnumpy(cost))
 
-                if callable(new_cost_fn):
-                    cost_fn = new_cost_fn
-                    if not cost_fn_modified:
-                        cost_fn_modified = True
-                        self.callback_history["orig_cost"] = self.opt_history.copy()
+            if callable(new_cost_fn):
+                cost_fn = new_cost_fn
+                if not cost_fn_modified:
+                    cost_fn_modified = True
+                    self.callback_history["orig_cost"] = self.opt_history.copy()
 
     def apply_gradients(self, trainable_params, grads):
         """Apply gradients to variables.