We have 2 bathrooms in our house.. 1 toilet works fine, no real problems.. but the other toilet is very weak in terms of water pressure. What's the best way to get it going again?

Toilet doesn't seem very old.. not really sure how old it is.
Yes, a lazy flush, and yes, that has been the problem for a long time.

Does the water seem to just go around and around and really not go out of the bowl with any speed?? If so there is a chance that your bowl has a build up of lime in the bowl and up in the trap. If you see any brown stains coming out of the trap area or out of a small hole down in the water or up around the rim of the bowl it is lime deposits and the only to get rid of it is to clean it with something. I have suggested for people to use muriatic acid but most of the others on here do not recommend it so therefore I am not recommending it to you... Good luck