The game itself can be quite heavy on memory as most browser based game are. Playing it on lower spec PCs along with other applications can result in slowing down of the game and lag. Those users can also have issues when visiting other users maps who have lots of buildings. This is due to all the buildings moving and generating memory use.
It would be beneficial if possible to have a toggle animation option for these users to shut off the animated buildings. It could be easily done as the essentials could still be animated and buildings could be highlighted when buffed and still produce but without all the moving horses in stables etc.
Just an idea as most on-line browser based games have this...