Hi,
Could anyone please help with the following

1) i have mixed down a track in reason 3 and there is no clipping, but the CPU is still going crazy, i have also increased the CPU limit but i am still getting distortion crackling sounds and the CPU is hitting red. Is there any other explination why this could be happening. e.g my actaul RAM or Harddrive?

2) After a while i will also get this messege when trying to play the track 'Computer to slow to play song, please optimize the song'

Please help, Any suggestions will be appriciated.

Thanks

the simple answer is use less instruments and effects. If you are using combinators take a good look at the instruments and effects that it contains.
It's also worth looking at making any effects that you chained with a particular instrument global effects by assigning them to your mixer too. If you use a preset mastering combinator it might be worth ditching that too and mastering it yourself.

what kind of specs does your comp have? How much ram? processor speed?