Event: ARCH wait on SENDREQ

 I see the  "ARCH wait on SENDREQ" event as the top most event always. Here are my top 5:

Event                                               Waits    Time (s) Ela Time
-------------------------------------------- ------------ ----------- --------
ARCH wait on SENDREQ                                  310         413    50.98
db file scattered read                             20,674         159    19.66
CPU time                                                          156    19.21
db file sequential read                            11,801          69     8.52
SQL*Net more data to client                       106,682           4      .46
          -------------------------------------------------------------

We just implemented Standby database. Log archive destination parameters defined as,

log_archive_dest_1                   string      LOCATION=F:\arch\VOYOPER
log_archive_dest_2                   string      service=VOPRSTBY arch reopen=6

Please guide me how can I tune this as I see some slowness due to the above "ARCH wait on SENDREQ".