Novice Php Site Needs Optimization

SEO for Google, I saw most responders were probably 8th degree blackbelts in web design/optimization. I need a spoon-fed answer. I did not design my site. My designer quit web design & became a real estate broker. Now, I’m trying to pickup where he left off. He finished my site. But I’m now trying to optimize it. This site is all PHP. So, WOULD I BE WASTING MY TIME OPTIMIZING THE PAGES AS IF THEY WERE HTML (i.e., meta tags, keyword density, links, alt tags, keywords in URL, etc.) WITHOUT FIRST CHANGING ALL THE PHP CODING THAT “PREVENTS” PHP SITES FROM BEING OPTIMIZED?
I read some so-called “quick-fixes” to this problem elsewhere but it seemed I would need a PhD in computers to understand them.

php just spits out HTML (and usually the raw HTML is mixed in the php itself). Unless your base page (time to first byte) is really slow you don’t even need to touch the actual code. All of the optimization techniques would still apply.

What’s the site URL? Usually there’s some small changes which will make a huge speedup (on most sites)