[SOLVED] Project file size inexplicably bigger (due to nondestructive MIDI editing)

Is this because I split the drums into separate tracks?

I think we might have a winner.

Additional tracks = more disc space yes?

I don't think this is a problem, and anyway, a 4MB file is absolutely TINY by today's standards.

Additional tracks = more disc space yes?

We're talking MIDI, not audio, so I don't understand why moving events to different tracks should radically increase the amount of data.

Each MIDI event has 7 values: track, time, channel, event type, and 3 "data" values.

Changing the track value of a MIDI event should not increase the data size at all, at least in terms of uncompressed data.  Sonar's compression algorithm might benefit from keeping the events in the same track (or channel, or event type), but it's hard to believe it would matter by a factor of more than 2, since there are 6 other values for each MIDI event.

Also, I've done this sort of drum track splitting on all my other projects, and never noticed the project file size increasing significantly.

I'm wondering if I accidentally turned on nondestructive MIDI editing or something else that might be inflating the data, even though I can't see it (and it doesn't appear in the event lists).  Could anything else explain why moving MIDI events to different tracks would dramatically inflate the file size?

But, you had to create the additional tracks in order to move your Midi events from the original, single track yes?

Actually, sorry, but that assumption is incorrect; I didn't add any MIDI tracks. 

My default project template has 8 MIDI drum tracks, all empty.  On the first day of this project, I recorded to the first drum track, leaving the other 7 drum tracks empty.  Yesterday, I simply moved notes from the first drum track to the empty drum tracks (e.g., toms to the "toms" track, snares to the "snare" track, etc.).  I do this on all my projects, which is why I have those 8 MIDI drum tracks in my default template.

So the project has the same number of MIDI tracks before and after the drum splitting. 

(I actually deleted some of the empty audio tracks, so the project has fewer overall tracks.)

Other ideas?

Thanks, bitflipper! Your "never delete anything" comment gave me an idea:

I turned non-destructive MIDI editing off, and now the file is a little smaller than it was the first day.

Problem solved!