I love Vivaldi but it definitely chugs with the stupid amount of hibernated tabs I've got. The new sessions thing helped alleviate that a bit since I can save a window state and close it but I definitely run into some kind of memory leak with it. (I have had like 1k+ hibernated tabs open, so not entirely unexpected that it runs into issues but I'd still think if they're hibernated they should just be stubbed out tabs in memory until clicking one turns it into a full browser process. Idk)