If you encounter performance problems on macOS, you may want to try this tip: go to Help | Edit Custom VM Options, and add -Dsun.java2d.metal=false. This will tell the IDE to use its OpenGL renderer instead of Metal.
Metal support is still under development in JetBrains IDEs, and you may encounter various issues, such as a significant drop in performance over time. That’s why it’s best to try the good old OpenGL rendering engine. Meanwhile, keep in mind this is not magic, and the OpenGL pipeline has its own problems, especially when using an external monitor.
You may want to read and up-vote these issues: JBR-4699, JBR-4597, JBR-9916, JBR-5145, JBR-5063, and JBR-9859.
Also, using a more recent JBR can help, but it’s risky.
Finally, if everything is working properly, continue using the Metal rendering engine. The OpenGL pipeline is neither better nor faster. Performance and stability depend on your machine and operating system, as well as the version of the IDE and its JBR.