Alternatives to Cubase SX?

I have a copy of Cubase SX 1 which I have used for over a year now. I used to run it on a 450mhz G4 with a MIDI keyboard (with which it's performance was just about acceptable for simple pieces of music.) Now I run it on an 800mhz iBook G4 with a MIDI keyboard, a guitar via an iMic and a software based MIDI controller. My knowledge of music has also grown a lot over the past year, but whenever I compose an even slightly more complex piece of music Cubase's performance suffers terribly. Now, with what are still very simple compositions the software is pretty much useless. Every VST effect or instrument uses up about 20% of my processor power, and there are some very nasty bugs which attack at the worst possible times. After spending nearly £500 on this a year ago there's no way I'm spending over £300 again on an upgrade when my machine only just meets its system requirements and Steinberg's support for Mac users seems to be declining rapidly.



What other options are there? The obvious is of course is Logic Express, this looks a very reasonable price, especially if I can get an educational discount (as this is only for use as a hobby.) But would I get better performance and support? Or would there be any features I would miss from Cubase SX?



I'm not worried about compatibility with other users. Firstly, I'm a Mac user so I'm pretty used to being incompatible with everyone else, and also I'm only a hobbyist, not a creative professional. So there may be a less well-known program that would be good for me. I've heard good things about Digital Performer which seems to have cross-grade offers and is highly recommended by Danny Elfman. However this does look very high-end professional and I'm on a tight budget.



Any advice or opinions on this would be very appreciated.



Andrew