Can be situational, lots of topics i have on vpns, routers, technology, buffering and much more discussing this.
Ipvanish performance seems to vary, it also depends on your internet speeds, the device you have installed on and even version of android os installed. Alot of apps work much better on 7.1 or higher. Lots of different things are involved.
When i used Ipvanish i didnt have much issues. I have 1gig down and 50 up, while on it was around 90 to 150.