Don’t use client side includes!
- The performance hit of enabling SSIs is usually greatly over-stated. Modern web servers are usually hugely powerful machines. Many sites dynamically generate every page using technologies such as PHP or Perl, which carry far higher overheads than simple SSIs.
If your host doesn’t support some form of server side include, you should move to another host. The hosting market is saturated these days and good quality hosting with all the frills for a moderately trafficed site shouldn’t set you back more than five or ten dollars a month. Note that that’s assuming you go with an open source platform; proprietary hosting platforms can cost quite a bit more.