Excelente plugging de uso diario. Muy útil y funcional. Recomendable.

I've never encountered the issues mentioned by previous reviewer 'Anonymous user 2eb8bd'.
No slowdown here, never has any been as far as I can remember, including latest Firefox 59.0.3 (x64) / Windows 7 (x64).

My hesitation to use this 'Netcraft Anti-Phishing' extension is all in the fact such extensions (those which don't rely on local databases) contact their data servers on every page visited by the user. This hesitation is seriously leveraged by what I know of the extension's developer and, when it comes to Netcraft, I, we know the company is not a tracker : whatever, wherever you search on the Web, the company is noted positively. Yet I dislike -- even for my good -- knowing that everywhere I go (Web included) is echoed somewhere... over the rainbow :=)

Beyond my psychology remains this : the extension is efficient, it is fast, it is honest. Hence 5 stars.