The StackExchange question helped and my ego is on the verge of being crushed. Basically I let all the timers (25) start at the same time.
That is something that even my little Java concurrency experience should have told me can not be right.
For some reason I thought I could just set the time I want the CPU to be idle with setTimeout.
After I multiplied that time with the image index (0 to 24) it completes faster and it is more responsive, even if it is still a little bumpy.
I need to get better at thinking about what to change and play with when I struggle with this kind of problem.
Stupid brain ...