I have tried with the upload cap turned off, with a little higher than my capacity and 999999kB/sec which is within my capacity w/o any changes. 
 
The problem is that if I upload to an ftp directly from local browser, I reach only around 20% of the upload speed I get compared with fxp from my own ftp-server, that resides on the same computer, to other ftp's. 
 
I have made sure that the receiving ftp is not a bottleneck, and it's not only against one ftp, but several. 
 
myftp<-- fxp -->ftp1 -- 800+ kB/s 
local<-- normal ftp -->ftp1 -- 160kB/s
		 
		
		
		
		
		
		
		
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