Can some kind soul explain to me why the following is happening please? I somehow managed to download the whole MSFS again instead of just the update, so had plenty of time to either sleep, watch paint dry or see what was happening under the bonnet using Task Master. What surprised me was that the CPU was ticking over at circa 10% load but that the GPU was racing around between 40% and 70% load with a temperature of circa 70 degrees. I am not very clever with PCs but would have expected the CPU to do all of the processing of data as it was downloading, not the GPU. Which is correct please?

Decompressing on GPU? 

I believe the CPU is taking care of the decompression, as I'm seeing increased usage during this process, while GPU usage remains high and constant even when downloading. It's probably because it keeps trying to draw the interface at the maximum possible frame rate (still don't know why this would use so much GPU but who knows).

The solution to this is to use a frame rate limiter. I use the RivaTuner Statistics Server (via MSI Afterburner) and it works fine. Setting the limit to 1 FPS reduces GPU usage to around 1%, however I think this could also affect the decompression speed (or perhaps it's just the UI updating slowly), so you could increase the limit to 20 when the big files are getting decompressed to ensure a faster process.