XWeather breaks 3 to 4 time a year. This is why I use xOAPweather plugin. In the years I have been running it I've had no real problems. And the sourcecode is there if I need it.
mine's been running fast, and i do my update every 20 min. it could be the zip codes you are trying to download. their might be an issue on the weather side, on specific servers that hold the data for the zipcode you are trying to get.