Transient power supply with LM317 and LM2576
Connect the buck converter output to C1, not to the output of LM317. This will reduce current through LM317 and reduce power wasted as head in LM317 too.
Also add ceramic decoupling caps on the input of the buck converter. Something like two 1-10µF MLCCs of appropriate voltage, placed and routed for low inductance. You also need at least one MLCC on the output, like 10µF 6.3V.