scook is right... softsynths on the front end are your resource hogs. Once the tracking is done, your plugins chew up resources next. Freezing is great....I like to FREEZE, drag and drop the "frozen" into an audio track.... UNFREEZE and keep working. Once you unfreeze, you can drag and drop the "midi" data into a blank midi track just to save for reference, if you will be changing the softsynth settings, just make notes to go back to :)