PST Capture Tool - what speeds should we expect

I am using the PST Capture tool to import pst files into O365.  What speeds should I expect for these transfers?  At what point does Microsoft throttle the inbound files?

Is the only way to get multiple PST's importing to set up multiple PST Capture servers?

In this scenario what would be the maximum number of active threads into the MS data centre?

Many thanks

Jon