Cubase 12 Pro - Audio Performnace spikes Overshoots Asio Guard/Peaks

Even with few instruments tracks and with buffer size 2040 experienecing cracking noises . Its getting very difficult to mix the sessions . Infact on Cubase 11 never experineced such issue or audiodrop out.
Windows 10.
Computer:Intel(R) Core™ i9-9900KF CPU @ 3.60GHz 3.60 GHz
Audio Interface: RME Fireface UC

PLease suggest solution or any settings. Tried disabling Asio guard for VSTs , but still there.