Some final notes on performance

[Ian Brown]

I think I've figured out that the differences between 0.8.1 and 0.9.1
are because 0.9.1 ends up having to swap, while 0.8.1 did not.  This
might be a result of the larger 1.1 class files.

After running some other tests, I see that overall performance is
probably somewhat better.  In particular, where with 0.8.1 running
different size blocks made little difference going from 400 to 51200
bytes/frame, 0.9.1 is about twice as fast at the 400 bytes/frame level
and about equal at the 51200 bytes/frame sizes.

Ian