I did the upgrade from version 7 to version 9 in March, but enough is enough. I’m going to reinstall version 7, if this is still possible.
Here are the problems:
Version 9 is much, slower than version 7. It takes several seconds to open an email in a new window, and the search function is painfully slow. In version 7 the search function was really fast. I don’t understand what you have done.
The display of the folders in the column to the left, which was compact and neat in version 7, is now a mess in version 9. There is an unnecessary amount of vertical space which is used and some folders are simply hidden. I have to click on “more” to see them.
Message threading is a big mess. Emails are hidden in the threads, and you can’t see the chronological sequence of the emails.
Version 7 simply worked without problems as it should, version 9 is just a mess.
You can adjust that in Menu > Settings > Appearance > Lists.
They are called conversations. Messages are displayed in sequence in the conversation. It makes it easier for you see the whole conversation made up of messages in multiple folders in one place rather than having to search through your messages to find them. If you don’t want to use them, you can disable them using Menu > View > Conversations > Disable Conversations.
More is a place to hide folders you do not ordinarily want to see. That is why it is always collapsed on start. To add a folder to more, right-click on it and choose Hide. To remove a folder from More, right-click on it and choose Show.
Server searching is only as fast as the server does the search and returns the results. You can disable server searching by unselecting the option in the search box drop-down. Local searching can be slow if the database is stored on an old mechanical disk whereas SSDs are 100s of times faster with read/write, so that could be a cause.
Also, be aware we are about to release version 10, which has many improvements. Maybe try again when that is available.