Well this is an odd one. There seems to be odd behavior related to the photos app and the runtime broker that can cause severe lag in other applications. This problem is repeatable on my end.
Image 1: Normally when photos is open but not being used disk and CPU usage is zero. However when Photos has been left on for an extended period of time (10 - 30 minutes) even without interacting with it in any way it begins using a weirdly large amount of cpu and a huge disk read rate (single largest disk usage of any process)
Image 2 and 3: During this behavior of high photos disk usage, the runtime broker activates and deactivates on a oscillating cycle also using a large amount of disk and pushing disk active time to 100%. Again no user interaction at this point. you can literally sit and watch the task manager, touching nothing, and that cycle of usage continues. This disk usage is severe enough to cause system hangs as all other programs need to wait for the drive to free up in order to load anything.
Image 4: Closing the Photos app causes this behavior to immediately cease and disk usage returns to normal.