zfs discuss - Sep 2007 - different/high atch/s, pflt/s, vflt/s on two systems

hello,  a puzzle i hope you can shed some light on:

I have two systems, built at different times, but running very similar
software configurations (same hardware, patch rev).  They *should* have
near-identical load, as they are performing the same function in
parallel behind a load balancer.

However:  system#2 is noticeably and consistently slower than system#1
(both are under high load):

# sar -p 2 5

SunOS *system#1* 5.10 Generic_125100-10 sun4u    09/26/2007

14:47:32  atch/s  pgin/s ppgin/s  pflt/s  vflt/s slock/s
14:47:34   28.77    0.00    0.00 3439.18  196.59    0.00
14:47:36   23.69    0.00    0.00 2989.68  289.74    0.00
14:47:38   25.76    0.00    0.00 3312.57  270.75    0.00
14:47:40   17.61    0.00    0.00 1456.07  230.99    0.00
14:47:42   16.02    0.00    0.00 1474.72  140.62    0.00

Average    22.37    0.00    0.00 2534.78  225.69    0.00

# sar -p 2 5

SunOS *system#2* 5.10 Generic_125100-10 sun4u    09/26/2007

14:45:51  atch/s  pgin/s ppgin/s  pflt/s  vflt/s slock/s
14:45:53  371.08    0.00    0.00 19009.31 1405.88    0.00
14:45:55   55.12    0.00    0.00  124.88  454.63    0.00
14:45:57  381.28    0.00    0.00 15695.57  993.60    0.00
14:45:59  149.51    0.00    0.00 19591.18 1829.90    0.00
14:46:01  125.00    0.00    0.00 12613.73 1639.71    0.00

Average   216.08    0.00    0.00 13391.67 1264.22    0.00


system #2 has a zfspool and a few (zfs) filesystems, which system#1
doesn''t have.  Otherwise, I''m unsure of what might be causing
this.
Thoughts on what I should be looking at?

much thanks,
Jonathan.