[saagarjha]

No, this is wrong. Performance is everyone's responsibility, because compilers are fundamentally garbage-in-garbage-out. The people that work on them are incredibly smart and I don't want to discount that, but there is fundamentally nothing they can do if you write something nontrivial that's O(n^3): that's on you to fix. The fact is that a lot of websites leave timers running in the background or use really inefficient ways to manipulate the DOM, and despite the work of all major browser vendors there's not much that can be done here except asking the people that make those websites to not do this. If you're one of them, you should make it your responsibility to care about performance.