Have you maybe configured it to search online or something?

I have used TB for years and still use it daily, daily getting some 30+ emails, that I tag and sort into folders and all that. My TB profile is several GB in size. Search is instant for me, on all my hardware, including older laptops and even an old X200, with some upgraded parts.

I am not sure how it could be slow, so I am guessing something like your search needs to look for things online maybe, instead of in small inboxes and local folders.

>several GB

I have all of my mail going back to 2001..

I have all my email going back to then too. Many GB. I always download all of it locally. The global search bar (which searches all of it) appears instantaneous. It must be well under under 200ms. Every time I've verified the result with grep the results are accurate. I have no idea how they get it so fast.

Searching within a folder is different. It does a linear scan. If you don't search the body it's fast enough - a few seconds I guess on a big folder. If you search the body of the email in a big file, then yes it can take a while.

The Spacing isn't that weird. It just wraps paragraphs inside of paragraph tags. If you use Shift-enter you get a new line w/out a paragraph. The only real change I've had to do there is just hit enter once, where I used to hit twice.