Google XML sitemap and sitemap

I am facing errors in generating sitemaps for wordpress sites due to large number of posts. I have posted this issue to varoius forums but still did not received good reply. I got few replies that it is due to web host server resources but how to resolve it? As I cannot buy my own server. I have to run my sites and shared server.

My issue is that I am running various wordpress blogs like https://jobs-for-indians.co.in and https://dugg.pk and some others. I am using wordpress 2.9.2 at my said blogs. I am using Dagon Design Sitemap Generator to display site map at my blogs and Google XML Sitemaps generator plug-in but whenever my posts grow both plugins give errors of server resources and they don’t work. In response to my earlier posts I got few replies that it is due to web server resource issue but is there any way by which I can resolve the issue by having my sites at shared server as I cannot have a dedicated server. I have tried various shared web host but every where I faced same issue.