Since the last two updates InDesign is running very slow. There is a lag when I'm switching tools and moving between two open files. Using macOS Catalina (version 10.15.7), do I need to update to macOS Big Sur?
The cause may not be InDesign, but Catalina. Many people report various problems with Catalina. After installing Catalina I needed to perform a Clean Install, because my Time Machine Backups did not stop anymore. Suspected reason: Over a few years of installing new Macs and new OS 10 from TimeMachine backups, hundredthousands of small files consumed around 150 GB in the various libraries! A few apps (in my case the Mail archive...) could pile up many data in the user library.
With an early 2017 iMac I had system problems while using CS6 und Sierra: the system ejected randomly external hard drives, programs did not react etc.. Apple support looked in my system, and suspected in many such cases the Adobe programs. After long tests with Adobe free partitions. I finally I got the iMac replaced with a newer model. Just an observation: When I use Photoshop CC/Camera RAW and batch process some 50 images, the cooling fan goes "high" and very warm air blows out – that was not the case with the "corrupt" iMac that had no "progressive" cooling, so the processor chip might have overheated...
After installing Big Sure, my Macs run smoothly, never any program that "blocked" and does not react.
Sorry to hear about this. You may upgrade your OS to macOS Big Sur. You may also try following steps given below to improve the performance of the app:
**Please note that resetting preferences will remove all the custom settings and InDesign will launch with default settings. This way all your old settings will be saved in .old folders and InDesign will recreate new folders with default settings.
That is an expert advice!
Indirectly I might have solved a similar problem after installing Catalina (...and overloaded libraries) by a following Clean Install, which takes some time and preparations before taking such measures.