excel on macbook is very slow on responding or sometimes even not responding

Mostly and widely Microsoft Excel is developed for Microsoft Windows and is often optimized for Windows.

Have you tried any basic troubleshooting like safe mode {Start up your Mac in safe mode - Apple Support}?

Is this a with any/all excel files or particular to few/single excel file?

Where is you excel files located? (Local harddrive / External storage / Internet Cloud platforms … etc)

Usually if you are working with large data sets in Excel, it is bound to be slow on calculations which results in slow on responding/not responding.