For the first time in many years I took what I thought was common advice and wisdom and I’ve started using Mail.app on MacOS (Big Sur on Apple Silicon MBA). Three email accounts, one with 170,000 odd emails, another with 40,000 odd, and another with about 1000 emails. Mail.app is barely useable, so slow and it takes minutes to refresh when I change mailbox. Is this just Mail.app now or am I doing it wrong? Googling isn’t helping as there are so many bland articles on speeding up Mail.app. I’ve rebuilt the mailboxes, and I’ve even done the deleting index thing. Any ideas?