Just had a quick look at your log and yes, I can see it took 9 minutes to find a taxi route. We use two different algorithms, the first and fastest method returned an error of 'Unable to find a suitable connecting path to the destination'. If that fails (as it did here) we have a fallback method which, as you experienced, takes some time to complete. Having said that I believe you have a serious issue with your AFCAD file as I have never known such a thing at EGSS which is a relatively small airport when it comes to taxiways.
Your altitude issues were caused by you changing the altitude for waypoint #2 from 24,000 to 5,000, yet you chose to leave waypoint #1 and waypoint #3 at 24,000'
OK, now I remember that a lower altitude has to be preceded by something lower... Will remember that. The AFCAD for that airport is from the ORBX FTX England scenery, so other may run into that. I think I will re-fly that route and use the other runway for takeoff.