We LOVE log notes.  On average we store about 27 log notes for every current record in our database.  However, a bunch of those log notes are System type.  Combine comment, Sign-Up Comment, etc.
You can suppress them now with this toggle button:

 

 
You can control which log types are suppressed from the System Manager->Lists->Log Types menu.
 

 Open any log type you wish to suppress and check the box:
 
