diff --git a/rllib/connectors/action/pipeline.py b/rllib/connectors/action/pipeline.py
index dc10c60ce8bab..740b2b5f849bf 100644
--- a/rllib/connectors/action/pipeline.py
+++ b/rllib/connectors/action/pipeline.py
@@ -28,7 +28,6 @@ def __call__(self, ac_data: ActionConnectorDataType) -> ActionConnectorDataType:
             timer = self.timers[str(c)]
             with timer:
                 ac_data = c(ac_data)
-            timer.push_units_processed(1)
         return ac_data
 
     def to_state(self):
diff --git a/rllib/connectors/agent/pipeline.py b/rllib/connectors/agent/pipeline.py
index a34afdd04613d..480161bc5a413 100644
--- a/rllib/connectors/agent/pipeline.py
+++ b/rllib/connectors/agent/pipeline.py
@@ -39,7 +39,6 @@ def __call__(
             timer = self.timers[str(c)]
             with timer:
                 ret = c(ret)
-            timer.push_units_processed(1)
         return ret
 
     def to_state(self):
diff --git a/rllib/evaluation/collectors/agent_collector.py b/rllib/evaluation/collectors/agent_collector.py
index d8d02381e114c..afeda3b09d46f 100644
--- a/rllib/evaluation/collectors/agent_collector.py
+++ b/rllib/evaluation/collectors/agent_collector.py
@@ -1,14 +1,14 @@
+import copy
 import logging
-
-from copy import deepcopy
-from gymnasium.spaces import Space
 import math
+from typing import Any, Dict, List, Optional
+
 import numpy as np
 import tree  # pip install dm_tree
-from typing import Any, Dict, List, Optional
+from gymnasium.spaces import Space
 
-from ray.rllib.policy.view_requirement import ViewRequirement
 from ray.rllib.policy.sample_batch import SampleBatch
+from ray.rllib.policy.view_requirement import ViewRequirement
 from ray.rllib.utils.framework import try_import_tf, try_import_torch
 from ray.rllib.utils.spaces.space_utils import (
     flatten_to_single_ndarray,
@@ -20,7 +20,6 @@
     TensorType,
     ViewRequirementsDict,
 )
-
 from ray.util.annotations import PublicAPI
 
 logger = logging.getLogger(__name__)
@@ -38,6 +37,17 @@ def _to_float_np_array(v: List[Any]) -> np.ndarray:
     return arr
 
 
+def _get_buffered_slice_with_paddings(d, inds):
+    element_at_t = []
+    for index in inds:
+        if index < len(d):
+            element_at_t.append(d[index])
+        else:
+            # zero pad similar to the last element.
+            element_at_t.append(tree.map_structure(np.zeros_like, d[-1]))
+    return element_at_t
+
+
 @PublicAPI
 class AgentCollector:
     """Collects samples for one agent in one trajectory (episode).
@@ -230,8 +240,7 @@ def add_action_reward_next_obs(self, input_values: Dict[str, TensorType]) -> Non
             AgentCollector._next_unroll_id += 1
 
         # Next obs -> obs.
-        # TODO @kourosh: remove the in-place operations and get rid of this deepcopy.
-        values = deepcopy(input_values)
+        values = copy.copy(input_values)
         assert SampleBatch.OBS not in values
         values[SampleBatch.OBS] = values[SampleBatch.NEXT_OBS]
         del values[SampleBatch.NEXT_OBS]
@@ -356,8 +365,10 @@ def build_for_inference(self) -> SampleBatch:
                 # before the last one (len(d) - 2) and so on.
                 element_at_t = d[view_req.shift_arr + len(d) - 1]
                 if element_at_t.shape[0] == 1:
-                    # squeeze to remove the T dimension if it is 1.
-                    element_at_t = element_at_t.squeeze(0)
+                    # We'd normally squeeze here to remove the time dim, but we'll
+                    # simply use the time dim as the batch dim.
+                    data.append(element_at_t)
+                    continue
                 # add the batch dimension with [None]
                 data.append(element_at_t[None])
 
@@ -458,20 +469,20 @@ def build_for_training(
                     # handle the case where the inds are out of bounds from the end.
                     # if during the indexing any of the indices are out of bounds, we
                     # need to use padding on the end to fill in the missing indices.
-                    element_at_t = []
-                    for index in inds:
-                        if index < len(d):
-                            element_at_t.append(d[index])
-                        else:
-                            # zero pad similar to the last element.
-                            element_at_t.append(
-                                tree.map_structure(np.zeros_like, d[-1])
-                            )
-                    element_at_t = np.stack(element_at_t)
+                    # Create padding first time we encounter data
+                    if max(inds) < len(d):
+                        # Simple case where we can simply pick slices from buffer
+                        element_at_t = d[inds]
+                    else:
+                        # Case in which we have to pad because buffer has insufficient
+                        # length. This branch takes more time than simply picking
+                        # slices we try to avoid it.
+                        element_at_t = _get_buffered_slice_with_paddings(d, inds)
+                        element_at_t = np.stack(element_at_t)
 
                     if element_at_t.shape[0] == 1:
-                        # squeeze to remove the T dimension if it is 1.
-                        element_at_t = element_at_t.squeeze(0)
+                        # Remove the T dimension if it is 1.
+                        element_at_t = element_at_t[0]
                     shifted_data.append(element_at_t)
 
                 # in some multi-agent cases shifted_data may be an empty list.
diff --git a/rllib/evaluation/episode_v2.py b/rllib/evaluation/episode_v2.py
index 1dea86071253c..f0574366c9f4c 100644
--- a/rllib/evaluation/episode_v2.py
+++ b/rllib/evaluation/episode_v2.py
@@ -1,5 +1,6 @@
 import random
 from collections import defaultdict
+import numpy as np
 from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Tuple
 
 from ray.rllib.env.base_env import _DUMMY_AGENT_ID
@@ -295,7 +296,7 @@ def postprocess_episode(
 
             if (
                 not pre_batch.is_single_trajectory()
-                or len(set(pre_batch[SampleBatch.EPS_ID])) > 1
+                or len(np.unique(pre_batch[SampleBatch.EPS_ID])) > 1
             ):
                 raise ValueError(
                     "Batches sent to postprocessing must only contain steps "