diff --git a/synapse/storage/databases/main/event_federation.py b/synapse/storage/databases/main/event_federation.py
index 9da9723674..1121709656 100644
--- a/synapse/storage/databases/main/event_federation.py
+++ b/synapse/storage/databases/main/event_federation.py
@@ -21,7 +21,6 @@
 import datetime
 import itertools
 import logging
-import time
 from queue import Empty, PriorityQueue
 from typing import (
     TYPE_CHECKING,
@@ -446,8 +445,6 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas
         chains_to_fetch_sorted = SortedSet(chains_to_fetch)
         chains_to_fetch_sorted.difference_update(found_cached_chains)
 
-        start_block = time.monotonic()
-
         while chains_to_fetch_sorted:
             batch2 = list(chains_to_fetch_sorted.islice(-BATCH_SIZE))
             chains_to_fetch_sorted.difference_update(batch2)
@@ -496,8 +493,6 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas
 
             yield links
 
-        end_block = time.monotonic()
-
     def _get_auth_chain_ids_txn(
         self, txn: LoggingTransaction, event_ids: Collection[str], include_given: bool
     ) -> Set[str]: