diff --git a/app/app.py b/app/app.py
index 8071d15..48811c4 100644
--- a/app/app.py
+++ b/app/app.py
@@ -1215,17 +1215,70 @@ def errors_banned_groups():
     banned_ips, banned_nets = _get_banned_ips()
     all_banned = sorted(banned_ips) + sorted(str(n) for n in banned_nets)
 
-    rep_ips = [b.split("/")[0] for b in all_banned]
-    asn_map = _batch_lookup_ip_asn(rep_ips)
+    # ── Étape 1 : reverse-index depuis les fichiers RIPE Stat locaux ──
+    # Les CIDRs bannis via "Ban AS" sont tous dans as_cache/AS*.json → zéro appel API
+    prefix_to_asn: dict = {}
+    if _AS_CACHE_DIR.exists():
+        for cf in _AS_CACHE_DIR.glob("AS*.json"):
+            try:
+                d = json.loads(cf.read_text())
+                asn = str(d.get("asn", cf.stem[2:]))
+                for p in d.get("prefixes", []):
+                    prefix_to_asn[p] = asn
+            except Exception:
+                pass
 
+    # ── Étape 2 : classer chaque entrée : connue (prefix cache) ou à chercher ──
+    entry_asn: dict = {}   # entry → asn string
+    known_asns: set = set()
+    needs_api: list = []   # entries non trouvées dans prefix cache
+
+    for entry in all_banned:
+        if entry in prefix_to_asn:
+            asn = prefix_to_asn[entry]
+            entry_asn[entry] = asn
+            known_asns.add(asn)
+        else:
+            needs_api.append(entry)
+
+    # ── Étape 3 : nom/pays des AS connus — 1 seule requête PostgreSQL ──
+    asn_details: dict = {}   # asn → {name, country}
+    if known_asns:
+        with _pg() as conn:
+            if conn:
+                try:
+                    with conn.cursor() as cur:
+                        cur.execute(
+                            "SELECT DISTINCT ON (asn) asn, name, country FROM ip_asn_cache "
+                            "WHERE asn = ANY(%s) ORDER BY asn, fetched_at DESC",
+                            (list(known_asns),)
+                        )
+                        for row in cur.fetchall():
+                            asn_details[row[0]] = {"name": row[1], "country": row[2]}
+                except Exception:
+                    try: conn.rollback()
+                    except: pass
+
+    # ── Étape 4 : lookup API pour les IPs/CIDRs bannis individuellement ──
+    if needs_api:
+        rep_ips = [e.split("/")[0] for e in needs_api]
+        ip_map = _batch_lookup_ip_asn(rep_ips)
+        for entry, rep_ip in zip(needs_api, rep_ips):
+            info = ip_map.get(rep_ip, {})
+            entry_asn[entry] = info.get("asn") or "?"
+            if info.get("asn"):
+                known_asns.add(info["asn"])
+                asn_details.setdefault(info["asn"], {"name": info.get("name", ""), "country": info.get("country", "")})
+
+    # ── Étape 5 : construire les groupes ──
     by_asn: dict = {}
-    for b_entry, rep_ip in zip(all_banned, rep_ips):
-        info = asn_map.get(rep_ip, {})
-        key = info.get("asn") or "?"
-        if key not in by_asn:
-            by_asn[key] = {"asn": info.get("asn", ""), "name": info.get("name", ""),
-                           "country": info.get("country", ""), "entries": []}
-        by_asn[key]["entries"].append(b_entry)
+    for entry in all_banned:
+        asn = entry_asn.get(entry, "?")
+        det = asn_details.get(asn, {})
+        if asn not in by_asn:
+            by_asn[asn] = {"asn": asn if asn != "?" else "", "name": det.get("name", ""),
+                           "country": det.get("country", ""), "entries": []}
+        by_asn[asn]["entries"].append(entry)
 
     groups = sorted(by_asn.values(), key=lambda g: len(g["entries"]), reverse=True)
     return jsonify({"groups": groups, "total": len(all_banned)})