Boost performance drops on very large systems

[cigamit]

Describe the bug
Boost performance in Cacti 1.2.x get's poorer the more data sources you have cached in the boost table to the point where it becomes unusable.

To Reproduce
Steps to reproduce the behavior:

1. Enable boost.
2. Cache as many as 25 million boost records
3. Observe the system performance when attempt to flush the boost cache. It may never complete.

Expected behavior
Boost should scale even as the number of records in the boost table increases dramatically.

[eschoeller]

That's a monster code update for boost!

[cigamit]

Well, sometimes it does not get fixed in the first pass. Now it's totally fixed here. #2962

Just a side note, there is no 'multiple process' boost right now. The setting is there, but it has not been merged. Our bad.