I've noticed Shareaza getting into ruts where it says "Connecting to the network..." for a very long time, and the Network tab shows a very large number of "dropped the connection unexpectedly". After a while, it occurred to me that "dropped the connection unexpectedly" probably means a RST packet, and that the most infamous source of these is the Great Firewall of China.
Sure enough, when this is happening the host cache tends to be full of TW, HK, and CN country codes.
It might be a good idea to make Shareaza detect which side of the GF you're on and either dump TW, HK, and CN hosts automatically, or dump all others, as appropriate, because apparently the Great Firewall is filtering Gnutella these days. Alternatively, given the way finding these hosts clumps in time it seems likely that specific host caches tend to have many great-firewalled hosts and others tend to have none, so distinguishing between two types of host caches would be another possibility.
In the meantime, manually clearing out the unreachable hosts doesn't seem to work very well. If a multi-item selection is made, and delete hit, it tends to delete more than the selected items for some reason. Deleting them one at a time is tedious. Doing either sometimes causes Shareaza to spontaneously exit, which is incorrect and extremely annoying behavior. Identifying GF'd-host-rich host caches to delete them seems infeasible since most have .com or .net (rather than .cn. .hk, or .tw) addresses and so do most other host caches, so there's no way to tell them apart in the host cache list.
On a side note, when Shareaza is running I get odd networking-related symptoms from other apps. Firefox randomly won't load pages until a link or refresh is banged on three or four times, though usually loads normally. Firefox also sometimes spontaneously acts as if "work offline" had been selected from the file menu, even though it hadn't. Thunderbird randomly won't fetch mail or newsgroups, then works again after waiting a while. Youtube videos pause randomly and need some prodding to resume. And so forth.