Time to First Byte is how long the browser waits before the server sends anything back. On cheap shared hosting, a TTFB over 800ms is common, and it makes every other optimization feel pointless — the page can’t start rendering until that first byte arrives.
On shared hosting you can’t change the hardware, but most slow TTFB is software, not silicon.
Cache first
The biggest win is page caching. Without it, every visit rebuilds the page from scratch — PHP runs, the database is queried, the theme assembles everything. A cache stores the finished HTML and serves it instantly. On LiteSpeed servers, install LiteSpeed Cache; elsewhere, use a solid caching plugin and enable full-page caching.
Then trim what runs on every request
Heavy plugins that hit the database on init — related-posts widgets, live visitor counters, some security scanners — add hundreds of milliseconds before the first byte. Audit them and cut what you don’t need. If your host offers Redis or Memcached, object caching keeps repeated queries in memory instead of re-running them.
Finally, put a CDN in front of the site. Even a free Cloudflare tier caches static assets at the edge and can serve cached pages closer to the visitor.
You won’t beat a dedicated server, but caching alone usually takes an 800ms TTFB under 200ms — without paying for an upgrade.