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I would take advantage of local optimisation if you have the potential to do so. I don't believe it would harm your national rankings as the locally focused result and inclusion in the local search results 10 pack would surely be better targeted to your audience than a nationally focused SERP. So what you lose on national placement when you have a local result which is suitable for the SERP, you will make up with improved context.

http://edgesoftmedia.ro/contact/ Adrian Luzaric is great

Sure, there are two areas to address on your server config. One is the cache-control which is returned in the header. I set a longer period of cache for all images and scripts to save users downloading new copies time and again to their cache.  ie: max-age=3600, must-revalidate - see more here: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html

Then I would also set some rules around using 304 status on page furniture and other assets which do not change frequently.

Aside from this, as far as I am aware, you should ensure your stack is optimised. The recent Search Insight session from Google was interesting as in that presentation they talked a lot about the average load and latency times they see, useful to use as a benchmark in tuning your own speed.

Cheers,

Damien