MAVSDK send rate

I’m using MAVSDK to send a custom message at a high frequency (1kHz) to a PX4 SITL simulation running on the same machine. However, using the mavlink status command, I can see that the received message rate is capped at 25Hz and most of the packets are lost:

 instance #1:
	GCS heartbeat valid
	mavlink chan: #1
	flow control: OFF
	  tx: 27988.0 B/s
	  txerr: 0.0 B/s
	  tx rate mult: 1.000
	  tx rate max: 4000000 B/s
	  rx: 28871.5 B/s
	  rx loss: 0.6%
	Received Messages:
	  sysid:245, compid:190, Total: 13088 (lost: 7358)
	    msgid:    4, Rate:  1.4 Hz, last 0.14s ago
	    msgid:    0, Rate:  1.0 Hz, last 0.16s ago
	    msgid:  446, Rate: 25.0 Hz, last 0.00s ago
	FTP enabled: YES, TX enabled: YES
	mode: Onboard
	MAVLink version: 2
	transport protocol: UDP (14580, remote port: 14540)
	Broadcast enabled: NO
	partner IP:
	ping statistics:
	  last: 0.00 ms
	  mean: 0.00 ms
	  max: 0.00 ms
	  min: 0.00 ms
	  dropped packets: 0

Is there a way to increase the rate at which the messages are sent to/received by PX4?