Wordpress speed

I built a wordpress website and found that the speed was too slow. The mainstream optimization is just to reduce plug-ins, optimize static resources, staticize website pages, etc. But for a website without plug-ins and using the default theme, the request for the PHP file itself takes 1 second. (excluding resource file loading), is this normal?

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Is this pot for WP or PHP?

I haven’t looked at the WordPress code in detail (because I’m not very familiar with PHP), but I looked at the WP database and found that there are only a few tables. Then I was thinking about so many websites based on WP extensions. What are the custom attributes? Isn't it implemented through post_meta? If this is the case, will each get_post_meta trigger a query? In that case, a page will be very slow. I don’t know if this is the case?