Very slow at the end (>=1.30)

[epixoip]

That's just the way it works. GPUs work on massively parallel problems, therefore you have to give them lots of work to do in order to gain acceleration. Once you start to run out of work, you start to lose acceleration. It's completely expected that it will slow down at the end.

This used to be much more dramatic in previous versions of oclHashcat, before atom added some code to adjust the workload once the final keyspace is approached. So you definitely don't want to "block" this, as the slow-down at the end would be much more dramatic without it.