loading 250kb include files, performance degration?

Hi there, I am working on a complex webapp written in php. Recently I was reading about performance issues and after analysing the code I found that most of the files load 5 external php include files to run. All together those include files make about 250KB (there are 5 files). Now I am wondering if loading 250KB on include files, each time a page = php script is called, is slowing down the webapplication a lot or not. Is this even noticable while surfing the site. I am wondering about response times since I found them a bit slow (the time I click on the link until the page starts to display). Thank you for any advice, Merlin PS: The system is a p4 2.4G with 1G RAM and about 500.000PI a month.