diff --git a/cmscontrib/loaders/italy_yaml.py b/cmscontrib/loaders/italy_yaml.py
index f8f5dd80b..f307522f9 100644
--- a/cmscontrib/loaders/italy_yaml.py
+++ b/cmscontrib/loaders/italy_yaml.py
@@ -27,7 +27,8 @@
 import os
 import os.path
 import sys
-from datetime import timedelta
+from datetime import datetime, timedelta, timezone
+from copy import deepcopy
 
 import yaml
 
@@ -39,7 +40,6 @@
 from cmscommon.constants import \
     SCORE_MODE_MAX, SCORE_MODE_MAX_SUBTASK, SCORE_MODE_MAX_TOKENED_LAST
 from cmscommon.crypto import build_password
-from cmscommon.datetime import make_datetime
 from cmscontrib import touch
 from .base_loader import ContestLoader, TaskLoader, UserLoader, TeamLoader, LANGUAGE_MAP
 
@@ -61,9 +61,15 @@ def getmtime(fname):
     return os.stat(fname).st_mtime
 
 
+yaml_cache = {}
+
 def load_yaml_from_path(path):
+    if path in yaml_cache:
+        return yaml_cache[path]
     with open(path, "rt", encoding="utf-8") as f:
-        return yaml.safe_load(f)
+        value = yaml.safe_load(f)
+    yaml_cache[path] = value
+    return deepcopy(value)
 
 
 def load(src, dst, src_name, dst_name=None, conv=lambda i: i):
@@ -118,6 +124,12 @@ def load(src, dst, src_name, dst_name=None, conv=lambda i: i):
         return conv(res)
 
 
+def parse_datetime(val):
+    if isinstance(val, (int, float)):
+        return datetime.fromtimestamp(val, timezone.utc)
+    return datetime.fromisoformat(val)
+
+
 def make_timedelta(t):
     return timedelta(seconds=t)
 
@@ -207,8 +219,8 @@ def get_contest(self):
             if args["token_gen_interval"].total_seconds() == 0:
                 args["token_gen_interval"] = timedelta(minutes=1)
 
-        load(conf, args, ["start", "inizio"], conv=make_datetime)
-        load(conf, args, ["stop", "fine"], conv=make_datetime)
+        load(conf, args, ["start", "inizio"], conv=parse_datetime)
+        load(conf, args, ["stop", "fine"], conv=parse_datetime)
         load(conf, args, ["per_user_time"], conv=make_timedelta)
         load(conf, args, ["timezone"])