Every year the program is larger, and your computer may be more out of date.

To Susan's point, you may like to check your system's configuration against the recommendations for the 2020 program: https://proconnect.intuit.com/community/product-system-requirements/help/2020-lacerte-system-require...

Just like all of us, every year Lacerte gets older and fatter, causing it to be slower.  

No, seriously, the program is larger and larger each year and there are more security protocols that run in the background.