Yeah, Obsidian should load much faster.
Have you tried to open a new vault to see if loading times are different/faster?
Make sure to update your theme under settings>appearance; recently Obsidian changed a lot IMO and this will break older, unmaintained themes.
Also, check always how old (latest update) your plugins are; both old themes/CSS snippets and plugins can cause errors and slowdowns.
Bad configurations, like poorly written dataview queries can cause slow performance or older obsidian plugins, like text expanders or search engines. But you seem to not have this kind of plugins installed.
I don’t actually know what deferred tabs mean…?
I would try and rename workspace.json in .obsidian vault config folder to workspace.json.bak (with Obsidian closed) and see what happens.
Additionally, a fresh Windows opening of Obsidian on startup may be thwarted by Windows Defender’s malware checks. But I don’t think such hindrance would occur because of that.