@Traps are gay this says it was 60fps during the first demo http://nintendoeverything.com/splatoon-2-global-testfire-tech-analysis-frame-rate-test/
Splatoon 2 Global Testfire - tech analysis + frame rate test - Nintendo Everything
The Splatoon 2 Global Testfire took place this past weekend, and Digital Foundry now has an analysis about its resolution and frame rate in particular. At least currently, we can expect Splatoon 2 to run at 1280×720 while in docked mode, and at a dynamic resolution while playing in handheld mode. It also has a rock-solid 60 frames per second....
nintendoeverything.com