sudden drop in statement turnaround latency -- yay!.

I took advantage of the holidays to update a production server (dual
Opteron on win2k) from an 11/16 build (about beta5 or so) to the latest
release candidate.  No configuration changes were made, just a binary
swap and a server stop/start.

I was shocked to see that statement latency dropped by a fairly large
margin.  Here is a log snippet taken as measured from the client
application:

0.000278866 sec:  data1_read_key_item_vendor_file_0 params: $1=005988
$2=002255
0.00032731  sec:  data1_read_key_item_link_file_1 params: $1=005988
0.000327063 sec:  data1_read_key_bm_header_file_0 params: $1=008704
0.000304915 sec:  data1_read_key_item_vendor_file_0 params: $1=008704
$2=000117
0.00029838  sec:  data1_read_key_item_link_file_1 params: $1=008704
0.0003252   sec:  data1_read_key_bm_header_file_0 params: $1=000268
0.000274747 sec:  data1_read_key_item_vendor_file_0 params: $1=000268
$2=000117
0.000324275 sec:  data1_read_key_item_link_file_1 params: $1=000268

These are statements that are run (AFIK) the fastest possible way, which
is using prepared statements over parse/bind.  The previous latencies
usually varied between .0005 and .0007 sec, but never below .5 ms for a
index read.  Now, as demonstated by the log, I'm getting times less than
half that figure.  I benchmarked a transversal over a bill of materials
(several thousand statements) and noticed about a 40% reduction in time
to complete the operation.

I wonder exactly what and when this happened, has anybody else noticed a
similar change?

Merlin