Giving a large folder from one avatar to another was causing a long delay when handled synchronously, since it took some time to retrieve the necessary data from the inventory service.
Handling this asynchronously instead stops this delay from disrupting all avatars in the scene. This has been shown in OSGrid.
I see no reason for not handling all IM messages asynchronously, just as incoming chat is handled asynchronously, so this has been switched for all instant messages.
Thanks to Nebadon for testing this change out.
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