Does anyone have this issue were firefox becomes slow if left open for a long time. In my case after a couple of weeks rendering becomes slow and when I use youtube for example if is laggy, just trying to change volume taka few second to show the volume bar. It also happens to my laptop at work. I have around 30 tabs open.
It’s either you need more RAM or you must learn to use a tab group extension. Also, if it gets slow, just restart it.
Simple Tab Groups is a nice add-on.
My personal favourite is Sidebery. It has vertical tabs and easily navigatable via mouse wheel. You can even unload a tab. And has tons of customization options.