Lagging of sketchup in even in an advanced pc

Why is my SketchUp 2021 lagging in Ryzen 9 5900x with RTX 3070 graphics, rendering in lumion works very fine but in sketchup even without any imported workshop model it lags too much.

Not much to go on.

Perhaps you could elaborate more on the problem or share an offending model…?

Any model with millions of edges and faces (see Model Info>Statistics with Show nested components enabled) will zoom and orbit slowly. Usually it is the 3D warehouse entourage elements (trees, cars, people, upholstered furniture) that are the culprits.

3D modelling applications are very CPU-intensive - and single threaded, so all the geometry in the model gets pushed through one of the processor cores. GPU performance is somewhat secondary here. Rendering applications work differently as they can split the model and process the parts separately in CPU cores and/or GPU cores.

Check if profile edges are on.

Profile edges are off, no cars trees or any other object has been placed, no tool used, only basic sketchup tools have been used…the model is working fine in my friends laptop with lower specs but in my pc it is orbiting and making edits very slow

Make sure SU is accessing your GPU and not your internal graphics card. Otherwise I would do a repair or reinstall of SU.