I have Centurylink DSL, and I've been having an issue lately.?

[Rute]

"What could be the problem?"
A ping time of 50ms is not a problem. Regardless, you think it is, so I'll give you my copy-pasta answer:

If you only knew how much goes into determining what your ping is. It’s not a static number. It will always be different. Just because its 10ms to one server, doesn't mean it’s always going to be 10ms. Your ping time is based on the speed and amount of traffic on your internet connection, the speed and amount of traffic on the server's internet connection, and the speed and amount of traffic on all of the routers in between you and your destination. If there's a bad router somewhere in Chicago, and you go through that router in order to connect to that server, then you'll have a bad ping time. There's nothing you can do about this. In fact, other than what you've done already, there's nothing further to be done to reduce your ping times. If you were to do a trace router to a server, you'd be able to see the number of routers you go through to get there, in addition to the time it takes them to respond. If just one of those routers shows a poor ping time, then that explains it. Since it’s not a router you have control of obviously, you just have to deal with it.