WordPress Performance and Archive options

I currently have a client that has a photography site. I continue to see the performance of the site degrade as she continues to upload photos. This client now has over 42k photographs in her media library and the site performance is very poor. I had WP Smush in place halfway thru and have gone back and smushed as many of the images as I could, but that has not helped. I only recently discovered the media file count after trying to take a backup of the site to work on in my local environment.

So…what can I do?

Are there any good options to Archive by month/year for WordPress data? My thoughts are similar to a database partition by year and set aside if it needs to be accessed.