I just played around with Vivaldi after seeing this thread. It definitely seems to have come along since first coming out...definitely the most customizable Chromium browser. I noticed that it seems to do well in benchmarks (similar to other Chromium browsers) but seemed a bit sluggish in actual use (responsiveness, page load speed, etc.)...especially compared to Edge and Firefox (I don't have Chrome installed). Compared to Firefox, it used less RAM...sometimes as much as half depending on the web site. However, I think I'll stick with Firefox, with Edge as my backup. While Firefox seems to not fare well in benchmarks, I've found the real-world use to be on par with the Chromium browsers...with cleaner interface. The performance of external adblockers (ublock, Adblock, Adguard, etc.) seems to work better than bundled ones. I'll definitely keep an eye on Vivaldi though as it continues to evolve.