draw speed performance drop

[23fx23]

im having a small issue, wich is hard to describe/debug

got a module where i dlike extremly fast resfresh onpaint (for vu meters, oscilloscopes and stuff like that)
so forced a repaint call on each bloc in process. i know its not that optimized, but thats kinda temp stress test, and in most cases it works, is extremly responsive and looks like say 60Fps
got one core at say 30 percent max.

however if i compile the module several times, on reopening the same patch, at some point the frame rates drop a lot and get suggilsh, like say 5 fps. (by the way its 3.0.166, HW accel on, TI 1080) , and i can observe one core then goes nearly 100 percent.

there doesn't seem to be memory leak in code, still got 25GB ram free, but maybe reallocationg problems or i don't know.. im not sure its code problem or usine related.
but i noticed that if i reboot the pc, then it becomes again fast AF.

any ideas what it could be?