Server is located in Netherlands. However if you have any problems or if anything is bugged just feel free to report it in the forums. Also these so called "lagspikes" for few people, just report them. I'll make sure to forward them aswell right to the Dev's.
I know that few bugs can be annoying but still it's a private server and it's not as easy to script as Wotlk (just to take AT as an example) Still the MOP S15 experience can be enjoyed and is by far better than Legion right now (if you ask me).