Startup options for Vivaldi are configured in Settings > Startup > Startup with section.
For example, start Vivaldi with:
- Last Session – Tabs and Windows that were open last time Vivaldi exited;
- Start Page with your Speed Dials;
- Pages configured under Specific Pages option.
When the browser is set to open with the Last Session, a good option to make it go faster is to Lazy Load the Tabs. That way only the active tab is loaded and other Tabs will fully load only when you go to them.
Furthermore, in case you’ve set the browser to open with the Last Session, but for some reason your previous tabs were not restored, click the Closed Tabs button on the far end of the Tab Bar or in the Window Panel to view and reopen recently closed Tabs and Windows.