EMB-505 Captain reported being unable to execute the required climb rate while trying to accomplish an RA maneuver; as directed by the TCAS system.

Narrative

On Vref to XXRL at approximately 1000 ft AGL received a TCAS RA commanding a climb and pitch attitude the aircraft was incapable of. (pitch attitude of 25 up) . Aircraft was light and fully configured during time of event. Power levers were at full and aircraft did little if nothing of a climb. Only after gear up and flaps were retracted to position 2 (when they were at 2 and not transitioning from full) did we get a meager climb rate out of the aircraft . Speed was at Vref to Vref plus 5 and the TCAS continued to command a vigorous nose up attitude. Only when passing through 1500 ft AGL did the RA conclude. We then were instructed to northbound at 8;000 ft and contact Departure. Upon a downwind with Departure another RA was executed due to VFR traffic off our right side. ATC apologized and said there were numerous targets; all VFR and doing their own thing. Base to final; thankfully was uneventful to landing.Although it was 30 degree centigrade outside during our RA; I expected more performances from this airframe than what we got. Coming from the CE-750 that had performance in spades; this event highlights the woefully under-powered design of this airframe. In short it was; pathetic. Plus I do believe there should be more horizontal separation from aircraft on parallel visual approaches; especially if there is a high density of training going on (flight schools etc.). And no one should be doing maneuvers so close to the primary airport.