Question: Does it really help to deactivate unused scripts with plugins like Perfmatters or Asset CleanUp to reduce server load (TTFB)?
This FAQ is not about asset unloading, CSS/JS optimization, Redis, page caching, or frontend rendering. It discusses a different layer of WordPress performance: preventing unnecessary plugin execution before the main document is generated. LiteCache Rush is mentioned because it is the implementation used here to explain this execution-layer approach.
Answer:
Partially - but less than most people assume, and not where it matters most.
Perfmatters and Asset CleanUp are legitimate tools that solve a real problem. Unnecessary CSS and JavaScript files add weight to the browser-facing output, increase render-blocking resources, and hurt Core Web Vitals scores. Removing them improves what the browser has to process after the page arrives. For frontend metrics - LCP, FCP, Total Blocking Time - that is genuinely useful.
But TTFB is a different measurement entirely. TTFB - Time to First Byte - measures how long your server takes to begin responding. It is a backend metric, not a frontend one. And this is where the limitation of script management tools becomes structurally visible.
Perfmatters and Asset CleanUp operate inside WordPress. By the time either tool can dequeue a script or suppress a stylesheet, WordPress has already completed its bootstrap. Every active plugin has already loaded. Every hook has already fired. Every database query triggered during initialization has already run. The script that Perfmatters then removes from the page output was produced by a plugin that already executed in full.
Removing the output does not undo the execution cost. The server already did the work. You just chose not to send the result to the browser.
That is why these tools improve frontend performance and PageSpeed scores without meaningfully improving TTFB. The server-side execution cost - which is what TTFB reflects - remains largely unchanged.
To actually reduce TTFB, you need to reduce what executes on the server before the response begins. That means fewer plugins running, less bootstrap overhead, and less initialization work per request - not less output after that work is already done.
LiteCache Rush operates at this earlier stage. Rather than removing assets from the page after plugins have already executed, Rush prevents unnecessary plugins from loading before WordPress runs. A plugin that never loads produces no execution overhead, no database queries, no hook registrations - and contributes nothing to your TTFB.
Perfmatters and Asset CleanUp make your pages leaner in the browser. Rush makes your server leaner before the response even starts. Both are useful - but only one of them actually moves TTFB.