[effitall]

Here's an odd one...

I'm working on a song that transitions from Verse to Chorus at bar 25. If I start playback at bar 21, this transition is smooth as butter. If I start playback at bar 20, the transition glitches disastrously.

Observations:

During normal playback, Total CPU tops out at 12% and mostly sits at 10%, RT CPU consistently sits at 7.3-7.5%.

When I start at bar 20, and things get glitchy at bar 24, RT CPU spikes. This spike does not occur when play starts from bar 21.

I'm going to attach a picture to reference in here.

This pic is the performance graph of Reaper during a few moments:

Spike 1 occurs when I selected bar 21. (Interestingly, RT CPU spikes occur any time I click anywhere in the timeline.)

After selecting bar 21, I press play until I reach bar 26 where I stop. Normal playback occurred during that time frame.

Spike 2 occurred when I selected bar 20 after stopping playback.

I pressed play, and during bar 24, you can see the bump in CPU again. (EDIT...In this pass the bump is really small...But I've seen this spike to 80-90% It only occurs when playback starts before bar 21)


What I've attempted to do so far:

Disable plugins. At this point plugs are fairly minimal. I'm using Superior Drummer 2, a few instances of ReaInsert (10), some 1973 EQ, some Voxengo HarmoniEQ (I feel this plug is problematic with Reaper), a couple of JS plugs, some other random bits.

It really doesn't seem to matter which plugins I disable, just as long as I disable something, playback clears up. For instance, if I disable all plugs, no issues. If I disable all ReaInserts, no issues. Or if I disable all HarmoniEQ, no issues. So I can't say it's a single buggy plugin, but rather the combination of plugins and routing within the project.

What I can't figure out is why it plays back just fine from bar 21, and not bar 20?! The other thing that's weird is it only happens in this ONE spot. I can play the whole tune up to bar 23 without issue, and I can play the whole tune from bar 21 with no issue. But I cannot play the whole tune.

Logically, you'd ask, "well...What happens are bar 24?" Nothing really interesting. Some automation moves. There are a couple of sound bits that start up at bar 23 and play over bar 24, but they have no processing. Again...It plays fine from bar 21, but not bar 20 or earlier.