If I make a search on some parameter or parameters that result in say >10 000 mails the RAM useage of KMail shoots up to easily over 1 Gb RAM. The RAM is not released if you close the search, you have to restart KMail
This bug has only been reported for versions before 4.14, which have been unsupported for at least two years now. Can anyone tell if this bug still present? If noone confirms this bug for a Framework-based version of kmail2 (version 5.0 or later, as part of KDE Applications 15.12 or later), it gets closed in about three months.
Just as announced in my last comment, I close this bug. If you encounter it again in a recent version (at least 5.0 aka 15.08), please open a new one unless it already exists. Thank you for all your input.