diff --git a/src/twfy_tools/utils/contact_io.py b/src/twfy_tools/utils/contact_io.py
index bd4f9de37a..953d17c727 100644
--- a/src/twfy_tools/utils/contact_io.py
+++ b/src/twfy_tools/utils/contact_io.py
@@ -3,6 +3,7 @@
 """
 
 from datetime import date, timedelta
+from functools import lru_cache
 
 from typer import Typer
 
@@ -14,9 +15,15 @@
 )
 from twfy_tools.db.models import OptinValues, User
 
+app = Typer()
+
 mailing_list_name = "mySociety Newsletters"
 
-app = Typer()
+
+@lru_cache
+def get_mailing_list_internal_id():
+    client = MailChimpHandler(config.MAILCHIMP_API_KEY)
+    return client.list_name_to_unique_id(mailing_list_name)
 
 
 def get_internal_optin_id(
@@ -25,7 +32,7 @@ def get_internal_optin_id(
     client = MailChimpHandler(config.MAILCHIMP_API_KEY)
 
     # get internal id for the mailing list
-    mailing_list_id = client.list_name_to_unique_id(mailing_list_name)
+    mailing_list_id = get_mailing_list_internal_id()
     interest_group_items = client.get_interest_group(mailing_list_id, interest_group)
     return interest_group_items.interest_name_to_id[interest_name]
 
@@ -62,7 +69,7 @@ def upload_contacts(start_date: date, end_date: date):
             members_and_values.append(MemberAndInterests(user.email, internal_ids))
 
     client = MailChimpHandler(config.MAILCHIMP_API_KEY)
-    mailing_list_id = client.list_name_to_unique_id(mailing_list_name)
+    mailing_list_id = get_mailing_list_internal_id()
 
     client.batch_add_to_different_interest_groups(mailing_list_id, members_and_values)