diff --git a/CHANGELOG.md b/CHANGELOG.md
index b0c7140d8..63ec79177 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Fix a bug: fix all failing tasks of rake task file chain.rake
 - Fix a bug: file_size_validator.rb was broken since ruby v3, see https://github.com/rails/rails/issues/41270
+- decreases sidekiq concurrency from 25 to 5, 25 is too much and consumes memory for nothing
 
 ## v6.2.0 2023 October 13
 
diff --git a/config/sidekiq.yml b/config/sidekiq.yml
index 1abddf065..4909a4622 100644
--- a/config/sidekiq.yml
+++ b/config/sidekiq.yml
@@ -1,7 +1,7 @@
 # configuration file for Sidekiq
 :verbose: true
 :logfile: ./log/sidekiq.log
-:concurrency:  25
+:concurrency: 5
 :queues:
   - [stripe, 7]
   - [default, 5]