Thank you for the reply.
Sorry, forgot to mention – OS Win 10 x64.
I did everything mentioned in 'Before posting' before creating this topic, except checking with other browsers – problem was with every webpage I opened.
A few hours ago I launched memtest86 (had three BSODs in a row), and seems I have troubles with one of my RAM sticks (2x8Gb Vengeance, which I bought on 7th of Dec). Since it is very likely to be a hardware problem, I believe we can close the topic.
Sorry for bothering and blaming Opera 🙂