Ordinary naturalisation in Switzerland requires ten years of lawful residence. It is a long process: certified language proficiency, proven integration, a clean criminal record, and passing the cantonal and federal checks one by one. It works. But it takes ten years.
What many people don’t realise is that there is a simplified procedure for those married to a Swiss national. The conditions are: you must have been married to that person for at least five years, have lived in Switzerland for a total of five years, and be integrated. Those five years of residence do not have to be consecutive. The result: you can apply for Swiss naturalisation via the simplified procedure (Art. 21 LN) without having to wait the ten years required under the standard procedure. This applies whether or not you hold a European passport.
There are two things you should be aware of before taking this for granted. Firstly, the marriage must be genuine. The cantons actively check that it is not a marriage of convenience, and the investigation can go quite far if there are any indications of this. It is not merely a theoretical check. Secondly: if the marriage breaks down before these conditions are met, you lose access to this simplified route. You revert to the standard ten-year route, except in very specific cases such as having children together who hold Swiss citizenship or having been a victim of domestic violence. It is not uncommon for someone to have been married to a Swiss national for four years, for the relationship to break down, and to then discover that the legal clock has been reset to zero. And that the ten-year period still lies ahead.