Yes in those example the email where quite large and spell-check is enabled, However this should not influence the client to this extend as it beachball literally for 3-5 second which with the computer in use is kind of hard to understand,

Thanks,

edit an email specially with large mail,

Editing a large message from "All Messages/Sent" or "All Messages/Drafts"? Or, are you just talking about composing a really long message?

Are you composing in HTML mode or plain text mode?

Are you pasting a long list of addresses in the To or CC fields before you start typing?

Is the progress bar showing in the mail panel (because Opera is checking for new mail etc.) when you're typing?

Is spell checking on? (right-click in body)

If Opera is being slow, I don't know what you could do to change besides avoiding the things above when you're typing if you find one of those things to be the culprit.

Are you edit a message in "All Messages/Sent" that has a large attachment?