v6.6 is 17% slower for adding index using tidb_ddl_enable_fast_reorg

[dbsid]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. turn on tidb_ddl_enable_fast_reorg
2. restore ossinsight dataset
3. alter table github_events add index test_idx(repo_id,type,action,closed_at,actor_login)

2. What did you expect to see? (Required)

no performance regression

3. What did you see instead (Required)

17% performance regression

4. What is your TiDB version? (Required)

v6.5