My catalog has over 325,000 and my production computer is a 2011 iMac. So I don't think you need to worry.

Also, if you hear that too many images listed in the catalog makes Lightroom Classic slow, that is false.

20,000 images isn't a lot. My catalog is now past 110,000 and it's doing great. Some pros have several times that number.

Hi there,

In addition to what Jim mentioned if you need any further information on the Lightroom catalogs you can refer the below mentioned articles.

How Lightroom Classic catalogs work: https://helpx.adobe.com/in/lightroom-classic/help/lightroom-catalog-basics.html

Lightroom Classic catalog FAQ: https://helpx.adobe.com/in/lightroom-classic/kb/catalog-faq-lightroom.html

Regards,

Nikunj

There is no limit to the number of images in a catalog. 20,000 is a relatively small catalog. You may not realize this, but the images are not actually "in" the catalog. The catalog is simply a database that keeps track of where the images are located on your computer as well as a record of the adjustments that have been made to those images. The images are simply stored in folders on your hard drives(s).