I have edited my first post for clarification, and yes the slow start applies each time the Testnet is reset.
They are targeting the z9 release next week to incorporate several bug fixes and hopefully stop the network issues. This will restart the Testnet so the block rewards will also be reset.
Also, default settings have Zcash run on a single thread. You can adjust the number of threads by setting genproclimit=4 (or your number of cores) in the zcash.conf file.
For hardware discussion see this thread: How to properly mine ZCash day 1? - #4 by zawy