S9Y sites hung after period of time

Damn. Somewhere march this year I reïnstalled my Synology NAS migrating all the data as well as reïnstalled the webserver software S9Y. Somehow this went wrong and as of then the two sites hosted on the Synology NAS were most of the time not responding or very slow. Until now. I cleared up a few database files, removed a few plugins and altered all articles to 'Allow comment' to disabled. What were the steps:

• Make sure you have a valid backup of the website and underlying database!
• Install phpMyAdmin and open it
• Connect to the database, in my case the MariaDB 10 database installed on the Synology NAS
• Browse to the table serendipity_entries and execute the following command:
  • UPDATE `serendipity_entries` SET `allow_comments` = 'false';
• Browse to the table serendipity_referrers. In my case a lot of rubbisch was in it and I cleared all:
  • DELETE FROM `serendipity_referrers`;
• Check all installed Event Plugins. In my case, running S9Y 2.4.0, some Event Plugins weren't supported. I deactivated the plugins first, tested and after that I removed a lot of them.

After these actions the sites run fine, also after a few days!