[MPlayer-users] rtc wasting 15% CPU

[RC]

I'm getting very strange behavior, and hope that somebody has a good
explanation for it.

I've got a 1.66GHz CPU and MPlayer uses about 15% of the time to play a
720x480 MPEG-2 video with just your standard default.

Now, if I use -nortc, the video appears to play exactly like before
(except for a very minor desync) but it uses up approximately 0% CPU... 
Practically no CPU time.

MPlayer's -benchmark output only shows insignificant differences:

RTC:    VC:   3.824s VO:   2.429s A:   0.264s Sys:  23.511s =  30.029s 
NORTC:  VC:   3.693s VO:   2.345s A:   0.261s Sys:  23.735s =  30.033s

The output of 'time' shows the real difference:

RTC:    5.06user 0.51system 0:32.09elapsed 17%CPU
NORTC: 0.19user 0.06system 0:30.96elapsed 0%CPU

I see the same thing with different VOs (xv/gl).  I've tried setting rtc
to various Hz values, from very low, to very high, without the slightest
change.  I'd really like to know why RTC is using up so much CPU time.