All abuse filters run twice for every file upload. This was introduced recently by me in 069e0c89a5e73cdb05f8d1f79e520ef560e9c30b (https://gerrit.wikimedia.org/r/#/c/295254/), accruing some tech debt to implement a long-requested feature, which allows Commons community to reduce the workload of file patrollers.
This is probably not a big deal in practice, because file uploads don't happen as often as edits, and because they're already slow. But there are some problems:
- Together with $wgAbuseFilterProfile, this causes log spam (T140518: Duplicate get(): "commonswiki:abusefilter:profile:…:…" fetched 2 times).
- If the filters match the action, but don't disallow it, the upload gets logged in the abuse log twice.
- And, well, obviously it's slower.