The game world is composed of several large blocks of landscape. Each of these blocks is different in the amount of effort that is required to render each frame by your PC.
You have the lowest visually intense landscape in the regions that deployed with the launch of the game in 2007.
In 2008, Eregion, Lothlorien and Moria came out as a step in visual quality and beauty and a performance hit on our PCs. Expansion 1
In 2009, Mirkwood came out with a second step up and a performance hit over Moria Expansion 2.
Great River and Dunland is a third step up in visual quality with a performance hit over Mirkwood. Expansion 3.
East Rohan and Wildermore is a fourth step in visual quality with a performance hit over Dunland and Great River. Expansion 4. This expansion introduced Mounted Combat for our characters and for our opponents. The Mounted Combat feature puts a lot of strain on Turbine's servers, our PCs and our internet connections.
West Rohan - Helms Deep - Expansion 5 - does not seem to be any worse than East Rohan.
You need to look into these possible solutions:
1) Get a SSD and put Lotro on the SSD. The churn of looking the textures - the visual elements into memory from the disk drive can really bog down the frame rate.
2) Lower your graphic setting so that each frame takes less work from your PC to render.
3) Verify that your internet connection is stable with a reasonable latency and low packet loss rate.
4) Kill all non essential processes like Skype to free resources.
Note: War Steeds outside of Mounted Combat areas do not generate much in the way of a performance hit because the Mounted Combat feature is turned off within the server and your PC software. All you have is the movement functionality.
Unless stated otherwise, all content in this post is My Personal Opinion.