This mod doesn't seem to make a difference, I and others still get CTDs unfortunately. Still feel free to try it, and if you should encounter a reduction in CTDs, please let me know

Wipes the Combat Log every 5 minutes, in the hope of reducing CTDs, without breaking addons that read information out of the combat log.

Please note: This is currently still untested. It may not work. It may even make things worse. It may break other addons. It may [insert some bad thing]...
But then, it just may do the trick.

If you notice and reduction in CTD with this addon, please let me know.
If you don't notice any, please let me know.
If you notice incompatabilities with addons, then ... oh well you get the picture.

Changing Frequency of wipes

Go to the Folder <Warhammer Directory>\Interface\AddOns\CombatLogClear and edit the file CombatLogCleaner.lua. In the 7th line you'll find "FREQUENCY = 300" change the 300 to any number of seconds you like. Maybe that helps.
Good luck