The problem was caused by creeping logic handling creeping left of first and
right of last characters. As result of logic error selections list doubled in
size after each creep and soon I got more than 10,000,000 records there bringing
Archy to hault. Revision 115.

Attempting to repeatedly creep right from the final document character (try
10 creeps in a row) permanently slows all of Archy down even across
restarts. CPU usage during any cursor movement goes from sipping 5-7% before
the slowdown to 100% after the slowdown. The Humane Document's size also grows 
much more rapidly than normal. This same bug also applies to the initial 
character. I assumed this was related to the run length encoding bug but it 
was not; It appears to be a behavior issue when applied to the first and last 
character.