每次都要查询dns，不会这么郁闷吧，也不知道windows host 文件对firefox起作用不？

network.dnsCacheEntries [Integer]

This setting determines how many entries should be held in the Firefox DNS (Domain Name System) cache. Whenever you enter a web address in Firefox, it needs to convert that text address into an IP number. It does this by looking up the name and IP number through a DNS server. By holding DNS entries in a local cache, the next time you want to go to the same site Firefox can load it up much faster. By default Firefox holds 20 entries in the cache. I recommend changing this number to match the number of sites you regularly browse each day. More importantly, check the setting below to ensure DNS entries are kept up to date.

据说默认是20个缓存条目，而且 about:config 里默认没有这个项目。

network.dnsCacheExpiration [Integer]

This setting determines how long the cached DNS entries (as set by the network.dnsCacheEntries setting) are held before they are discarded. The default is 60 (seconds), however before changing this setting consider the pros and cons - the longer cached entries are held, the quicker your browsing may be, but the longer it may take for Firefox to be aware that a site which was temporarily considered unavailable (unresolved) is now accessible (resolved).

默认60秒过期，很可能就是这个原因，一分钟够干什么呀…

我新建了这两个条目，不知道有用没，用一段时间再看… fasterfox 据说也有这个选项，我懒得装，不知道是不是一回事。谁知道，请留言赐教，谢谢。