I hit 100%, but often see stuttering/framerate drops.
Full Specs:
ASRock z170m Extreme 4 MB 8GB DDR4 2133 Dual Channel i5 6500 @ 3.2GHZ Turbos to 3.7 Radeon R7 240 2GB DDR3 (Carry over from old PC) 1TB Western Digital Blue 64MB cache HDD (Carry over) Windows 10 Pro
I have a sneaking suspicion the gfx card is the source of the performance issue. Its getting swapped for an RX480 in a few months anyway.
For giggles, I ran 5 instances of Higan .99 with the following games:
TMNT Turtles in Time Batman Returns Star Fox Contra 3 SMB 2 Yoshi's Island
All 5 instances ran simultaneously @ a solid 60fps, 100% CPU usage the whole time. No slowdown. Old Phenom II x4 struggled to run one of any SNES game in Higan @ 100%.