EXS 24 Logic Sampler Users Group

Since I got Logic 5.0.1 the other day I've been experimenting with the
EXS(TDM).
Could anyone throw some light on the following observations.
I have used up to 16 EXS24 at one time, playing groove control drum loops
and percussion plus bass. etc. There are 8 or 10 playing at the one time but
there are all 16 cranking away all over the place. This results in very
little movement of the Audio meter of the system performance display.
Everything works well.
However.......I ground my system to a halt by simply playing 4 EXS24's and 4
midi tracks!!  I loaded 2 pianos and 2 string patches. This resulted in a
"DTDM unable to communicate" error and the Audio meter peaking at 90 to 100%
But obviously the system performance has nothing to do with the size of the
samples in memory but with how many notes are playing simultaneously.
So I guess that system performance of the EXS is determined by polyphony .
I noticed that the 4 tracks that were playing had maybe 4 note chords
playing simultaneously.
In fact I noticed that the load of 1 EXS with a piano loaded is about the
same as instantiating an EVP88  and playing the same part.
Why is the EXS so power hungry when using a lot of polyphony?
PS The new VSM extension made no difference at all to the test.  I tried it
both on and off.
Phil Buckle.