First round of basic tuning work (shorter sleeps, larger BufferArray blocks).

Beefed up the metrics gathering in http_texture_load to get memory sizes and
cpu consumption on windows (still need to implement that on Mac & linux).
Ran runs with various idle loops with sleeps from 20 ms down to pure spinning,
varied Block allocation size from 1504 to 2^20 bytes.  2ms/2ms/65540 appears
to be a good spot under the test conditions (Win7, danu grid, client in Boston).