Default SAR command Solaris

SAR (default) command for showing general system reports.
sar -u ( it's default, same as if we only run sar without any option)

%usr: running UNIX processes ("user time")
%sys: processing kernel system calls on behalf of processes ("system time")
%wio: sitting around waiting to read/write data (to disks or network devices), as demanded by processes ("waiting for I/O")
%idle: just plain doing nothing as there were no processes that demanded the CPU's time ("idle").

if heavy %usr and %sys it may means a poorly written application can consume infinite amounts of CPU resources.
If %wio is high, your system is waiting for your I/O subsystems to catch up. You may have a slow disk or array. Check more with iostat.