AimIsADickThere is a difference between the two though; frametime states how long it takes to render a single frame. This is useful because it can tell the client if they have a bottleneck somewhere, need some stability or a frame cap, or just need to reduce the details, or whatever the solution is. Meanwhile frames per second merely state how many frames can be generated in a second, which can only tell the client if they are getting enough frames, and that means the client can miss out on tons of information crucial to proper optimization and it's extremely misleading if you get more than enough frames per second consistently.
P.S I did make one change to my OS: I changed my DNS provider to OpenDNS. Is this a good idea? Are there better options?
I mean, if you measure fps at the same resolution (every frame) that you're talking about, you will see the exact same variations. It really is the same metric.
Why are you mentioning DNS here?