> Any help how to fix this issue.

   Did you try a Web (or Forum) search for keywords like, say:
      hp-ux slow login
?  Similar complaints have been discussed many times in previous
threads.

> I tried trimming the wtmps wtmp btmp btmps but no result.

   As usual, showing actual commands with their actual output can be
more helpful than vague descriptions or interpretations.  However,
assuming that the problem does not involve over-large log files, another
common problem involves name resolution (DNS).  Specifically, the
FTP/SSH/Telnet/... server can't get the name of the client system
(whatever that is here) from its IP address.  The test (on the server)
is:

      nslookup ip.address.of.client

If that command is slow (to fail or succeed), then that may explain the
behavior you see.