[mattab]

Setup cron archiving is a must: http://piwik.org/docs/setup-auto-archiving/

For scaling tracking, QueuedTracking plugin is the solution: http://piwik.org/docs/setup-auto-archiving/

For managing DB size, see: https://piwik.org/docs/managing-your-databases-size/

For any other issue, maybe report in Github tracker: https://github.com/piwik/piwik/issues