Souce Monitor laggy playback

[demarrism6472864]

Typically there are playback issues with the Program Montior but with my new iMac that runs smoothly. My source monitor is super laggy though. It's hard to preview videos before putting them on the timeline. Any way to resolve this issue?

I'm editing 4K 120FPS clips.

[Kevin-Monahan]

Demarris,

What happens if you choose the Source panel menu > Close All and then reload the clip from the bin? Same? If so, have you tried trashing preferences? Let me know.

Thanks,

Kevin