<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=340640) </details> <!--IssueSummary end--> Suggestion from https://gitlab.com/gitlab-org/gitlab/-/merge_requests/68873#note_671872442 Do not use `then` in `BulkImports` transformers as it returns new copy of a hash, which contributes to memory consumption increase. Mutate local hash instead. Example: https://gitlab.com/gitlab-org/gitlab/blob/d8db3d37859d8d7795dfc85e8e3853821c55d628/lib/bulk_imports/groups/transformers/group_attributes_transformer.rb#L10-L10 Update all of the transformers where it's used.