diff --git a/cron.py b/cron.py
index fda5d4ef..436beca0 100644
--- a/cron.py
+++ b/cron.py
@@ -1,5 +1,7 @@
 import argparse
+import multiprocessing
 import urllib.parse
+from queue import Empty
 from time import sleep
 from typing import List, Tuple
 
@@ -761,47 +763,30 @@ def delete_old_monitoring():
     LOG.d("delete monitoring records older than %s, nb row %s", max_time, nb_row)
 
 
-def check_hibp():
+def _hibp_check(api_key, queue):
     """
-    Check all aliases on the HIBP (Have I Been Pwned) API
+    Uses a single API key to check the queue as fast as possible.
+
+    This function to be ran simultaneously (multiple _hibp_check functions with different keys on the same queue) to make maximum use of multiple API keys.
     """
-    LOG.d("Checking HIBP API for aliases in breaches")
+    while True:
+        try:
+            alias_id = queue.get_nowait()
+        except Empty:
+            return
 
-    if len(HIBP_API_KEYS) == 0:
-        LOG.exception("No HIBP API keys")
-        return
-
-    api_key_index = 0
-
-    LOG.d("Updating list of known breaches")
-    r = requests.get("https://haveibeenpwned.com/api/v3/breaches")
-    for entry in r.json():
-        Hibp.get_or_create(id=entry["Name"])
-
-    db.session.commit()
-
-    for alias in Alias.query.order_by(Alias.hibp_last_check.asc().nullsfirst()).all():
-        LOG.d("Checking %s on HIBP", alias)
-        if not alias.needs_hibp_scan():
-            LOG.d("Skipping %s, HIBP-checked too recently...", alias)
-            continue
-
-        # Only one request per API key per 1.5 seconds
-        if api_key_index >= len(HIBP_API_KEYS):
-            api_key_index = 0
-            sleep(1.5)
+        alias = Alias.get(alias_id)
+        LOG.d("Checking HIBP for %s", alias)
 
         request_headers = {
             "user-agent": "SimpleLogin",
-            "hibp-api-key": HIBP_API_KEYS[api_key_index],
+            "hibp-api-key": api_key,
         }
         r = requests.get(
             f"https://haveibeenpwned.com/api/v3/breachedaccount/{urllib.parse.quote(alias.email)}",
             headers=request_headers,
         )
 
-        api_key_index += 1
-
         if r.status_code == 200:
             # Breaches found
             alias.hibp_breaches = [Hibp.get_by(id=entry["Name"]) for entry in r.json()]
@@ -815,14 +800,66 @@ def check_hibp():
                 r.status_code,
                 r.text,
             )
-            continue
-
-        alias.hibp_last_check = arrow.utcnow()
+            return
 
+        db.session.add(alias)
         db.session.commit()
 
         LOG.d("Updated breaches info for %s", alias)
 
+        sleep(1.5)
+
+
+def check_hibp():
+    """
+    Check all aliases on the HIBP (Have I Been Pwned) API
+    """
+    LOG.d("Checking HIBP API for aliases in breaches")
+
+    if len(HIBP_API_KEYS) == 0:
+        LOG.exception("No HIBP API keys")
+        return
+
+    LOG.d("Updating list of known breaches")
+    r = requests.get("https://haveibeenpwned.com/api/v3/breaches")
+    for entry in r.json():
+        Hibp.get_or_create(id=entry["Name"])
+
+    db.session.commit()
+    LOG.d("Updated list of known breaches")
+
+    LOG.d("Preparing list of aliases to check")
+    queue = multiprocessing.Queue()
+    for alias in Alias.query.order_by(Alias.hibp_last_check.asc().nullsfirst()).all():
+        if not alias.needs_hibp_scan():
+            queue.put(alias.id)
+    LOG.d("Need to check about %s aliases", queue.qsize())
+
+    # Start one checking process per API key
+    # Each checking process will take one alias from the queue, get the info
+    # and then sleep for 1.5 seconds (due to HIBP API request limits)
+    checkers = []
+    for i in range(len(HIBP_API_KEYS)):
+        checker = multiprocessing.Process(
+            target=_hibp_check,
+            args=(
+                HIBP_API_KEYS[i],
+                queue,
+            ),
+        )
+        checkers.append(checker)
+        checker.start()
+
+    # Wait until all checking processes are done
+    while True:
+        sleep(5)
+        for checker in checkers:
+            if checker.is_alive():
+                break
+
+        # All are done
+        break
+
     LOG.d("Done checking HIBP API for aliases in breaches")