Okay, I've just reproduced my flight. In mid flight, head over to departure tab, click arrival BHX. As soon as I press ILS15 that's when everything freezes. Going to test this theory with 2 different airports to see if i still get the same result. I've included a screenshot this time of my fps counter with WASM enabled.
Edit: Just done a flight from EGCC-EKCH, zero issues when following the step I did above. However when i entered EGBB as ALTN and tried to program ILS15 arrival, that is where everything crashes. Not sure what it doesn't like about Birmingham, but glad it's not an i