"Archiving" Old Posts

Hi

My blog, http://www.systemlays.co.uk, has been around for a while and is now approaching 4,000 posts which is great.

However, i am wondering if this number will start to cause a drain on the overall site. I have recently encountered some problems with a couple of plugin's due to the number of posts.

So i was wondering if there was a way to 'archive' the oldests posts are reduce the weight they may have on the blog.

I am not sure if it is even an issue but i was thinking and so thought i would ask..

Thanks
Jon