Tactical plateau

I've been studying tactics a really long time and I've been stuck at the same level for a really long time.  I am currently at 1550 on chess.com tactics trainer and I've reached as high at 1700 on chesstempo.com in the standard mode.  My pass rate on chess.com tactics trainer is 65% and I've noticed that stronger players have closer to a 50% pass rating.  Obviously, I get punished for time.  Also, I've noticed that when I work on visualization drills, sometimes I see the board much better and my tactics skills momentarily increases and might ballon to a 1700 on the chess.com tactics trainer, but this usually fades in a short amount of time.  For you tactically stronger players, what would you suggest to get past this tactics ratings plateau aside from practice, practice, practice?