Have to pause between commands and to locate my mouse?

Could you post your Computer's DxDiag?

To gather a DxDiag on your computer, please follow the steps here: https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/

You can attach the txt file to your post directly. 

Sounds like you're running out of RAM, but that's for the EA folks to determine. To pause the game quickly, press 0 (zero) or P.

The mouse lag issue is normal in Sims 3 because of the massive memory leak from the style editor that EA refuses to acknowledge. Never seen it in Sims 4, though.

Here it is, 
Thanks

I do use the P key to pause quickly. 
Thankyou

Your computer is below minimum requirements on both graphcs chip and processor.

Don't think there's much you can do to make it faster.

It used to work perfectly on this laptop though, is there any reason it would just suddenly stop working? ☹️ 
I don't have any other computers so pretty gutted if this means I'll have to give up Sims, especially when I've just spent £60 on the expansions etc.

The more packs/patches you add, the more demanding the game gets.

If you're borderline already, adding more can put you over the edge.

I would try get a refund for the expansions you bought and play without them.