Hi Barleduq,
It's a stanza.co calendar, they provide game specific calendars. We are testing it out & we get money from them displaying their calendar (it has some ads sometimes). Other than the ads (if they're not blocked) it should be just html, css & small amount of js so it shouldn't really cause much increase in resource usage. I haven't noticed any increase on osx or windows but haven't tested any linux desktops.
I know wowhead recently had an issue with resource usage (but have quickly resolved it i believe)
https://www.reddit.com/r/wow/comment...otice_massive/ could that be it? You mentioned that you keep them open in a tab as well but said it persisted even after closing it so maybe thats not it?
Since you're on linux could you edit your host file and 127.0.0.1 www.stanza.co? That would disable loading the calendar. Do you still have high resource usage?