Just wondering as the last few days plotting courses of up to 900 LYr takes but a few seconds now compared to the long delays previous.
'Previous' when? As far as I'm aware, there haven't been any changes to the route plotter since they did some work on it with the Engineers update. It still tends to choke somewhat when plotting long distances in dense star fields, though not as badly as it used to some months back.
Are you near the centre of the galaxy (within 5kly). If so google "route plotting in the core". If not I dont know the bug you are talking about so cant help.