TeamCity performs cleanup too often and takes too long

Our TeamCity build server and  agent run in a Windows 7 Ultimate 32-bit box which is hibernated every  day when we leave the office. Since last week, every time we start it  next day it performs cleanup, which takes between 20 minutes and 2  hours. We've been using TeamCity for a long time now, since version 4.X  IIRC, and our projects have survived all those upgrades, with minor  changes, up to the latest version (6.5.6). Honestly, that's amazing.  Hats off to the developer team(s). Back to my problem:

• Disk  space doesn't seem to be the issue: Drive C (where TeamCity and Windows  are installed) has 114 GB of free space (from 232), and all other  drives, if it matters, have more than 50% free space.
• We use the  default internal database (HSQL). If moving to an external database  would improve the situation, we are willing to do it (we use SQL Server  Express 2008 R2 for our software, it would be nice if we could use it  for this as well).
• Cleanup policy is configured this way:
  • All projects, all build configuration
    • Clean everything more than 360 days older than the last build and older than the 360th successful build
    • Clean history more than 120 days older than the last build and older than the 120th successful build
    • Clean artifacts more than 120 days older than the last build and older than the 120th successful build
    • Prevent dependency artifacts cleanup
• The  next scan is scheduled for tomorrow at 3:00, so tomorrow it will  cleanup again. I attached today's build server log so you can see how it  came to that decision. I couldn't see it (looking at today's cleanup  related log entries, I don't see where that decision is taken).