Ice and Fire dragons made the tps go to 0

Hello! I am having quite a bit of trouble with the ice and fire mod. When I started up my fire dragon by holding down the space button to make it fly(stage 4), it made the server lag a ton. No one could rejoin once we've been kicked out for "Lost Connection". There were no errors, it just kicked us out; after a while, the tps would go from 20 to 0 instantly then register us as out of the server. This only happens when I render my fire dragon (join the game since I'm riding on it). Help would be much appreciated.