I've run into occasional lag spikes over the past few weeks. Normally, my latency is, in most zones, about 65ms. Sometimes it goes up to 72-78ms.
Lag or latency can be caused by a number of factors, but it's basically the client to server to client connection, the quality of your own connection to your ISP, and is then modified by the route the connection needs to take between your own location and the server location. There can be intermittent regional problems that can negatively affect the connection quality. That's why I said I've had occasional latency spikes over the past few weeks, not constant problems.
If you're having constant issues, the first step is to reset your router or residential gateway. If that doesn't do much or any good, then contact your ISP and have their tech department run some remote tests to see if they can detect a good, strong signal to and from your equipment.
I guess it's easier to blame my ISP for all the lag spikes I'm getting for close to 3 weeks now. Probably nothing to do with merging of both US and AU servers... I've tried everything from my side to correct the lag issue but it's obvious that the source of the problem is not coming from my end... I've confirmed that by playing another MMO game (after logging into RoM to play for 30 minutes of painful lag) where there was absolutely no lag while playing for several hours.
Since RoM is lacking in customer services so losing regular players won't matter to them much, but to note that my RoM playing time is getting less and less. You don't have to be a genius to figure out where that is leading to.