One thing to look at is polyphony.

An arp can send a lot of notes to a cpu heavy synth, same with chorder.

Depends on what voices you're using etc.

Mmmm....solution?

timmorris wroteMmmm....solution?

Increase the latency of your sound card (buffer size), or buy a more powerful computer !!

Even if you buy a better computer you still have to balance what you want to do with what you're able to do.

You can render and bounce parts to cut down on processing and other things so you manage your resources.

Like if I have a lot going on I can do a mixdown and start a new song (sub song) and put the mixdown in it and track vox or guitar with fx then bring the results back to the main song, etc.

Also is your computer optimized for audio production? Good first step. Lot written here and on the web about that subject.