High Population Servers Causing Lag?
None of the above. Lag is part of the internet. Distance from server + how many hops your packets take to the server = lag or ping time.
If there is a routing issue and a node is broken or overloaded or having a nice party with it’s DDoS friends you will encounter higher than normal ping times (lag).
If it is recent, contact your ISP and get them to investigate, they’ll always blame your equipment, it’s cheaper to do that for them than it is to find the real problem and have to spend lots of money repairing their equipment or spending the time to work with backbone companies. However, if you keep pressing them they’ll eventually work out where the issue is and get it fixed.
All of the ‘worlds’ are hosted in the same datacenters (NA and EU have different datacenters) so transferring to a lower population one is pointless and only affects your WvW stuff.