SiteMap Warnings

I have been getting quite a few SiteMap Warnings in Google Webmaster Tools lately. The warnings are all related to high response time for pages.

Also when I am logged into my website via WordPress I get a lot of "Error Establishing DataBase Connection". I refresh the page and it usually is OK then.

This is only happening for websites that I have used WordPress for which I know can be slow. I have QuickCache installed to try to speed it up but I am still receiving these.

I know very little about the server side of website hosting/maintainence. Does this sound like a database problem I need to raise to my hosting company? These have just started to occur and unless the sitemap warning thing is new in Webmaster Tools, it is a recent problem. In the past I would get a "Error Establishing Connection" error every once in a long while but now it seems to happen daily and several times a day so I have to think that is related to the sitemap warnings.

My largest (and best performing) website gets these errors a lot and I can see a decline in site traffic and clicks. Unless it is a coincidence it is starting to hurt my wallet.

Any suggestions?