I use Umami. It definitely appears to have a lot less features than Matomo. I wouldn't say that necessarily means it uses less resources, though? An analytics server is probably spending 99.999% of its time just receiving a tiny HTTP event rather than drawing UI unless you are sat refreshing the stats all day.

Umami got rooted twice this month because of holes in React, partly because of the enormous complexity of that framework.

Just my two cents.