I have been using blender for over a year now but when I installed it on my new pc all the menus are slow. For example when I click on the view menu and then click off it again the menu takes about 3 seconds to slowly slide off screen. The rest of the interface is running smoothly but I’m sure you can see why this is a problem!
New PC usually equals old graphics drivers that came with it. Look at your vendors website for latest drivers.