We've found out that large EXS24 (Sampler) instruments in MainStage 3.5 and newer do load slowly sometimes.
In our experience through testing, smaller instruments that are using EXS24 like MainStage's factory library, the Sunday Upright, custom sampled pads and etc. all load instantly, it's just really large EXS24 (Sampler) instruments, which for Sunday Keys users is only the Sunday Grand based patches, fall into that category.
Click on the articles below for help with speeding up the MainStage load time:
- Restore an older version of MainStage from Time Machine- if you've used Time Machine to make regular backups, you should be able to revert to a previous version of MainStage
- Change the settings in MainStage's Sampler Preferences- this should shorten load times, even though it might not eliminate them entirely
- Manually remove patches from your concert via "Show Package Contents- this should allow your concert to open without trying to load the samples and then you can add patches back in
- Backup your Mac with Time Machine for ongoing protection
- Create a Backup Copy of MainStage and Use It
- Check out additional troubleshooting ideas from Apple