I use a Lenovo with a Celeron processor, 4GB of RAM, and Manjaro (Arch) Linux as my main computer for coding and browsing.
Swapping the HDD for an SSD and installing Linux, transformed this machine. Now it's fast enough for normal tasks, even for light photo retouching. And it loads web pages without issues. Faster with each new release of Brave.
Brave's Chromium engine is optimized for Chromebooks, which usually have low power processors, so it runs fine on almost any computer, even with Core 2 Duo processors from 2008.
I also have a Macbook Air from 2014, and it is plenty fast. If you have enough RAM, almost everything loads instantly.
To free up RAM, you can use a tab suspender or enable the battery and memory saver mode in 'chrome://flags'. Each Chromium tab creates a new process and eats a lot of memory.
https://blog.google/products/chrome/new-chrome-features-to-s...
https://chrome.google.com/webstore/search/tab%20suspender
You can speed up Firefox or any Chromium based browser even more by storing the browser cache in a RAM disk. I use a small 128MB cache in the RAM disk and it works great. There is plenty of information on the web to set this.
There is a quite a lot of power hidden by bloat, in these old laptops.