I've used MPUI-HCB over SMPlayer now for quite a while and I'm deeply impressed by its performance and usability.
The Interface shows up within a second even on slow machines and there are no depencies (all you need is mplayer.exe and mpui.exe)
Take a look here: http://sourceforge.net/projects/mpui-hcb/
What do you think? Give it a try.
I also recommend disabling the automatic popup for subtitle-download in the options.
I believe this tool does a better job than the "overweight"/slow SMPlayer GUI.