Is Firefox under performing because of its Rust powered engine, Servo?

Sorry this might sound like a rant but I am really disappointed in Firefox for the past couple of years. Firefox used to be my go to browser until a few years ago when the problems started appearing. On my old laptop with 2nd Gen i7 processor and 4gb RAM, I used to have more than 100 tabs open in all windows combined and Firefox could handle them without a hiccup(granted many sites were not that heavy 3-4 years ago but still compared to Chrome Firefox was miles better). Chrome always had a problem handling a lot of tabs(would show problems even at 30-40 tabs). But now I generally use a much powerful laptop(6th gen i7, 16gb ram, 980m graphics card) and Firefox's performance is just terrible. The element inspector is a joke compared to Chrome and completely unusable. While I can go from one element to another in Chrome very easily, in Firefox the jump is very slow and choppy and until a few versions ago, highlighting the nodes in the element inspector would not even work everytime. Now even when I have 10 tabs open in Firefox, it briefly shows a spinning wheel when I go back to a previous tab. Chrome's performance is much better now compared to Firefox. So, I am wondering if its because of the Rust powered Servo browser engine that derailed the performance of Firefox? I know Hacker News loves Rust dearly but lets be honest it has its share of warts and bugs. Will we ever get to see the once great Firefox in its full glory again? In hindsight, does the Firefox dev team regret using Rust instead of C++ for their browser engine?