System Information
Operating system: Windows 10
Graphics card: Radeon R7 M370

Blender Version
Broken: (example: 2.81a)

Short description of error
Boolean modifier is being calculated despite modifier being set to invisible to the viewport (and to the render too)

I am working with high density mesh and am making some boolean operations, was experimenting how to animate some transforms without making my machine lag and bumped in this minor bug

Exact steps for others to reproduce the error
Subsurf the default cube to the max (for a decent machine add a second subsurf modifier to the cube).
Add a second mesh (in my test a cube)
Add a boolean modifier to the ridiculously subdivided cube, pointing to the simple cube
Move around the simple cube - the dense mesh is being cut - viewport shall be lagging
Disable the viewport rendering of the bool modifier
Move around the simple cube - the dense mesh is entire - viewport still lagging

Thanks <3