diff --git a/src/psycop_feature_generation/timeseriesflattener/flattened_dataset.py b/src/psycop_feature_generation/timeseriesflattener/flattened_dataset.py
index d6a0ee0c..d7a9548a 100644
--- a/src/psycop_feature_generation/timeseriesflattener/flattened_dataset.py
+++ b/src/psycop_feature_generation/timeseriesflattener/flattened_dataset.py
@@ -1,6 +1,5 @@
 """Takes a time-series and flattens it into a set of prediction times with
 describing values."""
-
 import datetime as dt
 import os
 from collections.abc import Callable
@@ -9,10 +8,13 @@
 from pathlib import Path
 from typing import Any, Optional, Union
 
+import dask.dataframe as dd
 import numpy as np
 import pandas as pd
 from catalogue import Registry  # noqa # pylint: disable=unused-import
+from dask.diagnostics import ProgressBar
 from pandas import DataFrame
+from tqdm.dask import TqdmCallback
 from wasabi import Printer, msg
 
 from psycop_feature_generation.timeseriesflattener.resolve_multiple_functions import (
@@ -24,6 +26,8 @@
     generate_feature_colname,
 )
 
+ProgressBar().register()
+
 
 def select_and_assert_keys(dictionary: dict, key_list: list[str]) -> dict:
     """Keep only the keys in the dictionary that are in key_order, and orders
@@ -604,10 +608,18 @@ def add_temporal_predictors_from_list_of_argument_dictionaries(  # pylint: disab
         ]
 
         msg.info("Feature generation complete, concatenating")
-        concatenated_dfs = pd.concat(
-            flattened_predictor_dfs,
-            axis=1,
-        ).reset_index()
+
+        flattened_predictor_dds = [
+            dd.from_pandas(df, npartitions=6) for df in flattened_predictor_dfs
+        ]
+
+        # Concatenate with dask, and show progress bar
+        with TqdmCallback(desc="compute"):
+            concatenated_dfs = (
+                dd.concat(flattened_predictor_dds, axis=1, interleave_partitions=True)
+                .compute()  # Converts to pandas dataframe
+                .reset_index()
+            )
 
         self.df = pd.merge(
             self.df,