LR Classic slows to a halt showing video files after updating to MacOS Tahoe 26.0.1

Updated to macOS Tahoe 26.0.1. today and LR Classic will not play 4K videos even in Library mode - it grinds to a halt as soon as 'play' is pressed. Looking at Acitivity Monitor it shows VTDecoderXPCService taking up 2-300% of CPU resources. Play appears to continue in the background without moving the display and when it has finished the VT... file clears. Before this the laptop would play OK in Library mode but not really in Develop. LRC version 14.5.1 running on MacBook Air M2 with 8GB. Any fixes out there please or should I roll back the OS for now?

Thanks in advance.

Simon