you didn't give much info on why your using a proxy, although i would assume it's for anonymity and their free. i once used public anonymous proxies for the same purpose, although this usually wound up constantly having to look up new ones and as most of these proxies are for large privatized usage, not only will you be limited by the amount of seed to peer ratio if it low, but also by the number of other users that are using that proxy. if this is the case, use of a proxy for anonymity, and you want to continue this route, i would suggest using a program similar to Multiproxy, where the software allows speed checks and also has a built-in proxy identification tool (ie. public non-anonymous, cached, anonymous ... etc) or using the proxy when less people are accessing this route. although, i believe using a VPN, such as HMA is a much more secure route to take and whatever choice you use, ensure to the fastest site closest to you. As i use a PC ... windoze (i know, don't send me hate mail), a traceroute via a dos shell, in my case would determine where the problem might lie in the reduced speed.
Use of a ipfilter, to eliminate known problem peers intent on leeching or other actions can also slow your speed down considerably. in the "help and support" section, instructions are given on how to implement a ipfilter and google search will allot the user of an ipfilter file.
this is but one file that can be unzipped and placed in the proper location or left unzipped (i prefer the first choice, as the files are not that large):
once placed in the proper location, you can check the "Ip Filter" button at the top to ensure the ipfilter is installed.
once the download is started, clicking the "Transfers" button at the top and the "Trackers" tab at the bottom, remove all non-responsive trackers from the particular download.
everything else and some of what i have already mentioned is already detailed in the "Help & Support" section of this page, especially the section on alotted number of download/upload slots and the number of available peers or seeds, suggested for your connection speed.
other non-Tixati related network issues can be easily addressed by a simple internet search. (ie. temporarily blocking all other programs or non-system services that may be using your bandwidth, optimizing your ethernet adapter with Reg tools (throughput or bandwidth optimization) ... etc)
hope this helps. ... and "super seeding" is always appreciated i'm sure by everyone.