I'm using quite large stagger size files, 1048576 to be specific, setting CacheSize to a value lower than that actually result in much faster processing (51s vs 40s).
If you set CacheSize - 1048576 , miner's thread finding 1 best deadline in 1 file and put it's to Sender.
If you set CacheSize - 131072, miner's thread finding 8 best deadlines in 1 file and put it's to Sender, Sender sends first best deadline to server, waiting response too much time, after sending second deadline, waiting again
Setting the stagger size to 131072 is actually faster. Only takes 41-43 seconds to process all the plots, setting it to 1048576 it takes at least 53 seconds and the CPU utilization is not 100%, so bigger is not better in this case for some reason.