30 seconds to open Vivaldi on High Sierra
I just upgraded High Sierra. While Vivaldi was under Sierra the browser with the fastest opening, since this upgrade it is by far the slowest. It takes 30 to 40 seconds to open. I do not see anything special to the activity monitor. I reinstalled him. Do you have any advice? I only meet with Vivaldi.
Submit a bugreport. Generally I wouldn't advice updating to a new version of macOS right from the start of the first official release.
I haven't been able to replicate the OP's problem on my test bed, but I did notice some general system lag due to background processes reindexing things. I would be interested in hearing if the OP is still having that problem a day later.