It's doubtful you'd gain enough for you to notice if you're upgrading from Windows 7 or Windows 8/8.1. You'd gain more FPS by reinstalling windows (getting rid of all the junk files). If you're on anything older however, you may notice an improvement assuming 10 has drivers for all your hardware.
Windows 10 does support DirectX 12, and if your GPU can take advantage of any of its features, you may get better performance in games that use DirectX 12 when they are released.
Personally I like the look of 10, and its cloud/LAN features, so I would consider it worth the upgrade if you like it better.