Translations:Manual:Combating spam/121/en

The lookup in an externally-hosted blacklist typically adds no more than a few seconds to the time taken to save an edit. Unlike $1 settings, which must be loaded on each page read or write, the use of the DNS blacklist only takes place during registration or page edits. This leaves the speed at which the system can service page read requests (the bulk of your traffic) unaffected.