> Areas where I really would like good ad-blocking (youtube) are often not covered by these ad blockers.

uBlock Origin works perfectly fine to block YouTube ads.

> I always found browser extensions (including uBlock) had a pretty big performance hit

In various places (e.g. the wiki [1]) you can find benchmarks showing that webpages load faster, rather than slower.

[1]: https://github.com/gorhill/uBlock/wiki/Various-videos-showin...