But for real users, such a delay(?) is not too critical or is not exist at all. However, not so often as previous one and there (based on some feedbacks/opinions) a bit reduced speed of reaction against some sorts of threats. Current engine is also quite good and show 'best' results with different tests and awarded by some organizations.

The traditional signature-based (or slightly improved) engines used by them in recent years are always one of the best (or 'the best'). But such a discussion can be only with 'clear' requirements and points how to mark company 'any good or not'. Actually, I can to think about only two (or three) companies who really can be better or with one level with F-Secure. Some companies with much higher number of employees and 'money' - but still with not so good engineers, people around and quality, attention to 'simple' things (like privacy terms and so on). Famous by certain tools or activities or by another. Where F-Secure was pretty active on one field or another. In general, F-Secure (Data Fellows) founded in 1988 and their history with some waves and ages. Because F-Secure has some real benefits and advantages over any other companies, some things may be as with any of good companies or software, and some things can be not so lovely.

But good if you could to specify your own requirements for this kind of software. It is fine company and security solution. But I havent really heard much about F-Secure, and dont know if its any good.

Windows defender is a good antivirus