Anyone have any suggestions or known fixes for the following:
Whenever I do extensive MIDI editing to a drum track in the Piano Roll in MC 4 it seems like something is getting "full" (maybe memory... I don't know) . I am able to make some edits, but if I try to edit "too much" (I don't know where the limit is)  after a while MC 4 can't seem to copy+paste a MIDI track and saving takes quite a long time (several minutes).
 
An example: I have a song file. I used EZD to create the basic drum tracks by copying in the grooves, etc. Then I go back in and edit the MIDI notes in the piano roll using the pencil to add in fills, cymbals, etc.  I am running both Roland and EZD drum kits through the synth rack so I have two MIDI tracks in the track view for playback (Tracks 1 and 4). When I am finished editing the drums in the piano roll, I switch back to the track view and copy the entire MIDI track from track 1 (Roland) to track 4 (EZD).  This works just fine the first few times I copy+paste, But, as I continue editing, at some point, MC has decided I've given it too much information and starts to move VERY slowly. Meaning: Copying Track 1 to Track 4 (I use Ctrl+C and then Ctrl+v to move the track) takes SEVERAL MINUTES. It doesn't happen when I first open the file. It seems to accumulate during the session until I reach that magic tipping point where MC just seems to have a hard time with it. I have sort of found a way to work around this by copying and pasting a very short segment first. Then, if I copy the whole midi track it generally pastes OK. However, it doesn't always work and saving still takes a long time (several minutes as well.)
 
Things I have tried:
Defrag hard drive
Delete extra files (I have about 50% free hard drive space)
Saving MC files to different folder
Opening/Closing MC
 
My System setup:
Music Creator 4
EZ Drummer
Win XP
Not sure what audio drivers or other "stuff" I have.
Adjusted latency/buffer
 
I am not sure what is causing this but it would be great to find out. It kills my productivity. It sometimes takes 20 minutes or more just to get through editing one or two midi notes and then saving the file so I don't lose my work.
 
To clarify: I have used MC 4 for almost 7 years and have done many songs this way. It's only in the last few months that I have seen this behavior. Also, I have a friend who sends me MIDI tracks. If I copy and paste from his file into my file, there are no issues. I have only noticed this specific issue when I do manual editing in the piano roll.
 
Thanks for any help!

What sound card or audio interface are you using?
Open Windows Task Manager to see what else is going on while you're doing your editing.
Have you tried using Groove Looping instead of copy/paste?

What kind of PC: Processor type and amount of RAM? What kind of HDDs?

what updates have occurred in the computer in the last few months?
 
Even though the OS is no longer supported and updated by MS.... the other programs may still be updating..... especially the internet browsers and security software AV stuff.
 
If one of them did an upgrade, that could be the problem.
 
Use the RESTORE to a former date option and do a system restore back into the time when it was running fine. You said it has only happened in the last few months, so I'd pick a restore point in January and set it back. See if that solves the issue. 
 
Don't fear the restore. I have used it a number of times to fix issues. I also had to do a reinstall/upgrade to my browser since something in it screwed up. But the computer now runs perfectly.
 
I also had a problem where the computer was running slow. Loading slow, start up was slow, and there was only about 5% of the hard drive left. Nearly into panic mode..... pause .... breathe..... posted the problem here and someone came back to tell me to set my automatic backup restore drive segment to a smaller number. Seems it was set too high.... I did that, rebooted and the computer came up real fast and showed a good 60% of the HDD available..... so check that too.
 

MIDI tracks are just data, very very low amount of data.  much lower than audio tracks.  it should take only millisecs to perform a cut and paste of part of MIDI track.
 
if this started happening in the last few months then you have to look at what has happened in the last few months to your computer, like Herb is suggesting.  I would also suggest that you look at possible viruses and especially malware.  malware could easily be the culprit.  you might have something recording your actions on the computer and sending it somewhere, or trying to.

Thanks for the suggestions. I agree that somehow, something has changed in my set up. I'm pretty confident I don't have Malware since I clean my machine regularly with multiple programs. An update seems like a likely candidate. What seems odd to me is that over the course of starting a new song and finishing a new song it goes from "fine" to almost unusable. It seems like there must be something happening during the session that is causing it. I will try opening up some of my older files that never had the issue and see how they respond. Maybe I changed a setting without realizing it. Thanks everyone!
 

Check the sample rates. 44.1khz and 24 bits for recording should be standard.

Doing a little more looking today and I noticed that in December 2013 (when I had a MC crash) a temp file was created. For some reason, files after that date are MUCH larger than previous files. For example, one of my previous files of a completed song (multiple guitars, bass, drums, vox, backing vox, lead guitars, keys, etc.) had a file size of approximately 3 MB. This seems pretty average for most of my files. However, the files I am working on after Dec are huge. I have one file that is 22 MB. Another song, currently in progress, with only about 10 total tracks is already at 7 MB. So..........somehow I am adding something to these files or changed a setting, etc. Any thoughts?
 
Guitarhacker -  I checked sample rates..look good. Thanks! Also comparing global and project options between old and new. All seem to be the same. I can't help but think I must have checked a box somewhere in the settings that is saving versions or copies or something that is increasing the file size.

shut off the auto save function.
 
Do all saving manually. I save after any new track that I like, and also after editing and at regular intervals while editing.
 
Cake will remind you to save if you try to exit and have not saved it yet..... but always save as I mentioned above. You never know when windows will decide to "act up" and crash.