Incredible slowdown and CPU saturation on Camera Raw

Hello everyone, for some time I have a problem with CameraRaw. As soon as I open it my fans start up and the processor goes up to 400/600% occupancy. The GPU is almost never used (about 1%).
So Camera slows down incredibly and with each modification on a photo there is a huge latency time which means that I can hardly work anymore. I'm on an Imac 5k 27" i7 32gb / SSD 256gb / Radeon R9 M395. My graphics card is well recognized by Adobe. I don't understand. Help 🙂