I'm using Windows 10 (build 1803) with Java 1.8.0-181 and I am also "capped" at 67-68fps.
I have an i7 6700k Overclocked to 4.6Ghz, 32 GB of RAM and an Nvidia 1080ti at 4k.
For some strange reason, I used to get 72fps as well, but now I'm stuck at 68fps as well. PSX's fluid as it's always been though.
cheers
-E