You can configure a plugin to run in a dedicate process, or even in its own process.
See reaper.blog
- Native runs the plugin in the same process as Reaper. If it crashes, it brings down Reaper.
- Separate puts all 'separate' plugins in the same process, separate from Reaper. If one crashes, it brings down all separate plugins, but not Reaper.
- Dedicated runs each plugin instance in its own process.
I use dedicated for plugins like Largo 2 (which crashes if you change the channel count on a track), and plenty of IK stuff.