diff --git a/.gitignore b/.gitignore
index 8ca66d1..4b95e1d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -65,3 +65,5 @@ docs/_build/
 
 # PyBuilder
 target/
+*.idea*
+.venv*
diff --git a/src/georinex/tests/benchmark_obs3.py b/src/georinex/tests/benchmark_obs3.py
new file mode 100755
index 0000000..8148d79
--- /dev/null
+++ b/src/georinex/tests/benchmark_obs3.py
@@ -0,0 +1,72 @@
+import subprocess
+import timeit
+
+import numpy as np
+import pandas as pd
+from jan import janobs
+from pytest import approx
+import xarray
+from pathlib import Path
+from datetime import datetime
+import georinex as gr
+from plotly.subplots import make_subplots
+import plotly.graph_objects as go
+from src.georinex import obstime3
+
+R = Path(__file__).parent / "data"
+
+
+def run_obs3_parser(file_path):
+    #parsed = gr.load(file_path)
+    parsed = janobs(file_path)
+    ...
+
+
+def generate_data():
+    results_file = R / "obs3_sweep" / "benchmark.csv"
+    if results_file.exists():
+        return pd.read_csv(results_file)
+    base_file = R / "TLSE00FRA_R_20220010000_01D_30S_MO.rnx"
+    sweep_dir = R / "obs3_sweep"
+    sweep_dir.mkdir(exist_ok=True)
+    times = obstime3(base_file)
+    header = gr.rinexheader(base_file)
+    t_start = pd.Timestamp(np.min(times))
+    t_end = pd.Timestamp(np.max(times))
+    n_steps = 10
+    dt = (t_end - t_start) / n_steps
+    cases = []
+    for steps in range(1, n_steps, 1):
+        duration = dt * steps
+        slice_file = sweep_dir / f"{base_file.name}_slice_{duration / pd.Timedelta('1h'):.2f}h.rnx"
+        cmd = (f"gfzrnx_217_osx_intl64 -finp {base_file}"
+               f" -fout {slice_file}"
+               f" -epo_beg {t_start.strftime('%Y-%m-%d_%H%M%S')}"
+               f" -d {int(duration / pd.Timedelta('1s'))}")
+        if not slice_file.exists():
+            process_output = subprocess.run(cmd, shell=True, capture_output=True)
+            assert process_output.returncode == 0
+            print(f"Created {slice_file}")
+        print(f"Adding {slice_file} to the database ...")
+        cases.append({"epochs": (duration/pd.Timedelta('1s')) / float(header['INTERVAL']),
+                                "file": slice_file,})
+    for case in cases:
+        print(f"Processing {case}")
+        case["parsing_s"] = timeit.timeit(lambda: run_obs3_parser(case['file']), number=2)
+        case['epochs_per_second'] = case['epochs'] / case['parsing_s']
+        print(f"took {case['parsing_s']:.2f} s ({case['epochs_per_second']:.2f} epochs/s)")
+    df = pd.DataFrame(cases)
+    df.to_csv(results_file, index=False)
+
+
+if __name__ == "__main__":
+    df = generate_data()
+    df["file_size_mbytes"] = df.file.apply(lambda x: Path(x).stat().st_size) / 1e6
+    fig = make_subplots(rows=1, cols=1, shared_xaxes=True)
+    fig.add_trace(go.Scatter(x=df.file_size_mbytes, y=df.epochs_per_second, mode='lines+markers', name="Epochs per second"),
+                  row=1, col=1)
+    fig.update_layout(title_text="Performance of the Obs3 parser")
+    fig.update_xaxes(title_text="File size [MB]", row=1, col=1)
+    fig.update_yaxes(title_text="Epochs per second", range=[0,df.epochs_per_second.max()*1.1], row=1, col=1)
+    fig.show()
+    ...
diff --git a/src/georinex/tests/jan.py b/src/georinex/tests/jan.py
new file mode 100644
index 0000000..354d266
--- /dev/null
+++ b/src/georinex/tests/jan.py
@@ -0,0 +1,19 @@
+import pandas as pd
+
+
+def janobs(file_path):
+    df = pd.read_csv(file_path, sep='|', header=None)
+    df.columns = ["lines"]
+    i_end_of_header = df[df.lines.str.contains('END OF HEADER')].index[0]
+    header = df.iloc[:i_end_of_header]
+    df = df.iloc[i_end_of_header + 1:].reset_index(drop=True)
+    df["i"] = df.index
+    is_timestamp = df.lines.str.startswith('>')
+    timestamps = df[df.lines.str.startswith('>')]
+    timestamps['rx_time'] = pd.to_datetime(timestamps.lines.str[2:29], format="%Y %m %d %H %M %S.%f")
+    timestamps = timestamps.drop(columns='lines')
+    df = pd.merge_asof(df, timestamps, on='i', direction='backward').drop(columns='i')[~is_timestamp]
+    df = df[~is_timestamp]
+    df.columns = ["records", "timestamps"]
+    df["sv"] = df.records.str[:3]
+    ...
diff --git a/src/georinex/tests/test_nav3.py b/src/georinex/tests/test_nav3.py
index 103e98b..faede13 100755
--- a/src/georinex/tests/test_nav3.py
+++ b/src/georinex/tests/test_nav3.py
@@ -5,6 +5,7 @@
 from datetime import datetime
 import georinex as gr
 
+from src.georinex import rinexnav3
 
 R = Path(__file__).parent / "data"
 
@@ -212,6 +213,11 @@ def test_large_all(sv, size):
     assert dat.time.size == size  # manually counted from file
 
 
+def test_large_rinex3():
+    fn = R / "BRDC00IGS_R_20220010000_01D_MN.rnx"
+    rinexnav3(fn)
+
+
 @pytest.mark.parametrize(
     "rfn, ncfn",
     [