The appropriate thing to do would be to check reset signal using an oscilloscope but i don't have one here. Anyway, I simply wanted to ask if by any chance this could be due to some oversight related to how the non-optimized build could affect this, based on someone else experience with the same problem. But I guess it is pretty specific.
We can assume that the unoptimized code is correct (it usually is, the optimized code sometimes is not). Then the only effects of unoptimized code that I can think of might be:
1. Parts of the boot-up code assume that .data and .bss will not be used. These are initialized later after several startup functions have been called. What if unoptimized code were to require some global data initialization? This is possible but not likely.
2. Timing will be different. Delay loops will be much longer. If there is any critical code that assumes a quick action, that action will be delayed.
