WAITSTATS output...where is the real pain point?

Hi All,

While im on the MAXDOP high, i thought i'd pose another question for a waitstats output im getting from one of my OLTP servers:

If i order by waittime:

CXPACKET, has the greates percentage of waittime but the absolute avg seems quite low:

waittype, percentage, avg_wait_time_s

CXPACKET, 72.8, 0.0074

LATCH_EX, 8.2, 0.0029

PAGELATCH_EX, 3.7, 0.000

If i order by avg_wait_time_s, then its a different waittype

ASYNC_IO_COMPLETION, 0.8, 97.5 (!)

LCK_M_U, 0.2, 0.5

LCK_M_S, 0.2, 0.0

So looking at the top 3 'offenders' ordered by different criteria, which would you see is the real pain point or which area would i start investigating first?

Thanks in advance!