Simulations playing slowly is something we all have to work with. Ways to reduce this 'lag' are reducing the face count of your model, and using simple physics shapes rather than convex hulls. Try and reduce the number of physics-enabled objects as much as possible, and, in complex mechanisms, set as many parts as possible to 'no collision' (In the UI). This will stop them colliding with other objects, which is the main drag on the simulation speed.

Select it like any normal object, and hit 'delete' on your keyboard. Alternatively, you can use the move tool on it to get it where you want.