Simulink sample rate with Arduino way too low

I am currently working with Simulink for the first time. My task is to control a Testing-Stage for DC-Motors. I do that with a Arduino Mega 2560 and with Simulink on my Laptop. I am reading and writing some Pins for Voltage and Current control and to read some sensors. The Problem is that my Simulation ( dont think thats the right word for what i do here) should last for 10 seconds but those 10 seconds take like 100 seconds in Simulink. I need to check all the Pins at least 10 times per Second but this seems unpossible.

Currently my blocks are set to a sample rate of 0.1 or 1... but it still doesnt work in an accurate speed at all.

What do i do wrong? Removing the graphs and displays didnt help.

(I am forced to do it with simulink!)