Using English (GB) dictionary causes runtimebroker to go slightly mad

Hi.

If I set the spell checker to use English GB, I have to suffer significant delays when using SourceTree.

Using Taskmgr to see what the wait queues are, it seems SourceTree is waiting on RuntimeBroker.exe

Using Procmon to see what is going on there, I see MANY MANY thousands attempts to find a [random-name].dic file in my %temp% folder.

Turn off spell checking. Nice and fast again.
My temp folder is small in file count (less than 100 entries).
Happy to supply additional config if needed.