Need help with userscripts...

What scripts are you talking about? I'd assume that you mean userscripts, which you should use tampermonkey on chrome or greasemonkey on firefox to use. You'll probably install them from a site. They will slow down your browser yes, but only by a very small margin, normally unnoticable. The best ones are based off the sites you use. video2mp3 ones for youtube, etc.

for me

opera -> ---- tampermonkey -> ---- sg2o -> + sglinkies -> + sgv2dark -> + sgtools proflink ->

install = click to "install"

this thread has most of the scripts released for sg https://www.steamgifts.com/discussion/1SCgV/sg-add-ons-registry

you need a script manager depending on your browser

• Tampermonkey for Chrome
• Greasemonkey for Firefox
• Violentmonkey for Opera
• GreaseKit for Safari

they you can install scripts and test how they work, and if they are compatible.

Which ones are the best?

It is not a 'which ones are the best' question, it is a 'which ones fit my necessities' question