The preview window in tv is designed to compute its content asynchronously. This approach ensures smooth input handling and maintains overall UI responsiveness. You can test this yourself by using a custom preview command that simulates a delay, like so:
tv --preview "sleep 1 && echo 'the preview'"
You'll notice that even with a delay, the UI remains responsive and doesn't block.That said, I'm sure there's always room for improvement, and I'd be happy to hear your thoughts or suggestions if you're open to discussing it further.