RAM preview so slow on a high resolution monitor

[kiakima]

I recently purchased a new iMac and totally maxed it out. 

• iMac (Retina 5K, 27-inch, 2020)
• Processor 3.6 GHz 10-Core Intel Core i9
• 128 GB 2667 MHz DDR4
• Gfx card AMD Radeon Pro 5700 XT 16 GB

I have After Effects fully up to date v22.2.1

RAM preview no longer plays back at full speed. Even if I let it play through multiple times. The work-around I have found is to change my display resolution in the System Prefs by scaling the monitor. I have to scale it up the maximum amount to get my RAM previews back. (Which of course means the UI is all scaled up and annoyingly large.)

Is there any other way to make RAM previews work again? 

Thanks!

[P.M.B]

First most obvious question is do you have a dedicated cache drive and if so is it full?

Second is how long of span are trying to preview?

Third is what is going on in the project (how system intensive is it).