Blender’s current viewport performance isn’t that great. That being said, there are few things you can do to make it a bit faster.
Disable auto smooth in object properties if there are any that have it enabled.
Remove/disable normal map nodes in shaders.
Here’s a workaround to use instead so you don’t lose all the details: Way Faster Normal Map Node (for realtime animation playback with tangent space normals)
Disable subdivision in viewport.
Rendering wise the biggest performance hits in eevee are volumetrics, amount of lights with shadows, transparencies, SSR (especially if you are close up to a material) and heavy usage of depth of field.