About
This works only for html canvas (so the browser games or complex animations), not the videos/gifs or the browser in general. This might be useful when you want to unlock your browser fps lock to reduce input lag in games. This script by itself can not increase your fps in any way, but there is some info about that, scroll down to read it
Also you might find useful the Performance monitor along with this script
The script might not work at all. Make a discussion topic about the website where the script is expected to work but it isn't

The script uses icon from icons8.com
How to install to a PC browser
Step 1. Scripts manager
To use scripts, first you need to install a scripts manager. My advice is Tampermonkey, since I use it too
Tampermonkey install links for different browsers, choose yours:
Chrome / Vivaldi Opera Firefox Safari Microsoft Edge
If your browser is missing here, you can PM me on this website, and I will try to help you
Step 2. Come back here
Refresh the page and press the green Install button that is above this description
Step 3. Check if it works
It is? Oh wow
If you've got into some problems
This works tricky and there are 2 operation modes. Their purpose is to replace each other when one is not working.
In some cases they both might not work. If default mode 1 is doing nothing, try to switch to mode 2.
In some cases the mode 2 might destroy fps completely, but it wouldn't be sudden, you will see it
right after page refreshing if it's going to happen. If it is happened, this probably means that the page
has multiple "screens", and the mode 2 is currently working for some random single one of them. You
can refresh the page multiple times to try to randomly set the limiter to the screen you need, but if this
doesn't help, or you don't like this, and the mode 1 is not working too, this script can't really do nothing more
More
More fps always leads to less input lag which is really useful in games, but a browsers by default are restricting fps to your monitor refresh rate (e.g. 60). You can remove this restriction, but your fps might be way too high after that, causing some another problems... That's why this script might be useful, but this topic is complicated, and different people might get different performance results with different combinations of options, so you need to try a different approaches by yourself