If you use Photos for Mac to sync your photos to iCloud, you may have been through this situation: «Photo Agent» application is working at full capacity. This occurs when working with the Mac in processes that require little resources, the fans of the Mac begin to actively work. The best way to check which program is consuming so many resources is to open activity monitor, which you will find on the dashboard or by invoking it with spotlight. Once you access the program, look for the CPU tab to know what program is squeezing your Mac's processor, if it is Photo Agent, who is above 30%, this is what is happening.
It is not a problem with the operating system, nor with the photos application, a priori everything works as it should. Unlike, MacOS is synchronizing the information we have in the Photos application with the information we have in iCloud: the images, but also the metadata of the photos, and the faces recognized in them. Depending on the number of photos, the process will take more or less.
This does not mean that it is somewhat annoying at times, especially when we work in a less powerful team. However, the process tends to integrate quite well with the rest of the functions and should not reduce resources of tasks that we are working on at the moment.
Still, we can stop the process, temporarily, or permanently. The latter is only recommended if you don't use Photos as the default photo program.
For temporarily paralyze the process, we must access the photo preferences. To do this, we will open photos and click on preferences, by clicking on the photos text in the upper bar, or by clicking Cmd + (comma). Now, select the iCloud tab and click on: pause for a day. The photo agent process will pause for one day.
On the other hand, if you want to stop the process completely, go to System preferences, look for the option iCloud, and click on photos. This way, Photo Agent will not connect again. Remember, your photos in iCloud won't sync on this Mac.