SMD resistor high current pulses

[BennoG]

And if you look at the datasheet curve, it assumes the LED is somehow kept at rated temperature (say 25degC). Which is a fair assumption with very low average duty cycle and short pulses (short pulses with large intervals). But if the LED heats up, the light output drops further than expected from the curve. I suggest you measure the light output and find a sweet spot for maximized light output but not at any cost, i.e. stop where returns are diminishing.

Yes monitored the temperature with a thermal camera after 1 hour it i about 5C above ambient temperature.