Try software upgrades or ease up on some advanced security settings if it is within your security policy to do so. If not the best option would be to upscale your MX to MX450.
You can also try to reduce the amount of tunnels that terminate if its a vpn hub. You can do this by disabeling the active active tunnel on your spokes. Failover will be slow but you can conserve a good amount of system resources that way as well.
MLL
