The other day I went to buy a DDR stick but the shop was closed so the only solution was to sit down and fix some memory hungry applications ;).
These will be in 4.11:
* Fixed a bug where maildir resource would use 1 or 2GB when importing large folders.
* Fixed a bug where mixedmaildir resource would also use 1 or 2GB.
* akonadiserver wasn't clearing uneeded query caches. Saved 65MB here.
* Kontact had 5 copies of all calendaring data in memory if you used summary view which
* KOrganizer grew infinitely over night under some circumstances.
* KAlarm wasn't freeing editor dialogs, resulting in infinite memory usage over time.
* Mysql got up to 25 MB of savings (4.12)
Also, Dan Vratil and Vishesh Handa have been working hard on performance/memory of nepomuk and akonadi.
To be continued...