They do have free version still if you created account before 2021
I have gaming pc so i did not had any performance issues with sophos, but for low end pc its not most efficient choice i guess, there are many more lightweight antiviruses out there
And reason why i ditched it was because there are cheaper alternatives with better protection, also sophos ui / dashboard is pretty outdated, its been same for like 5-8 years (cant even remember how long) and they dont add new features or have major updates on sophos home.
But i still think its reputable choice if youre sophos fanatic