Simulink - Sample Time

To speed up development I've used this LCD library (16x2)

https://github.com/RaphvK/arduinoSimulink/wiki/QuickStart-Guide:-LCD

The issue now is that some of my systems run at the wrong rate, the delay for my momentary switch is supposed to be 3 seconds but doesn't activate until 6. Then the sine wave that drives the servo also takes twice as long to complete.

If I remove the LCD code then everything is fine, I've rebuilt the model this morning to troubleshoot where the problem was coming from. I've also used another LCD library from the Add-On repository and had the same issue.

This is all running on an Arduino Mega 2560.