It just means that your account is not allocated enough memory on the server you're on. Either upgrade to a better server or try using the compress feed configuration option. And if compressing still doesn't work and you can't/don't want to get a better server, you will likely have to select the configuration option to start and stop the feed at a certain number. So start at 0 and stop at 2000, then redo it for 2001 to 4000. Or whatever number you need to be able to get it to not time out. I use the commercial version so I am not sure what settings are/aren't available in the free one, so my suggestions might be moot.