Hi! I recently joined Meta as an E4 MLE ( from a DS background, not SWE). I am super-excited to be here and looking to ramp up and onboard as efficiently as possible. Would love advice from senior members who have gone through the process. My major concerns :
Your first question is on pace and the second is on Impact. That's the wrong order.
Start with Impact and the pace will work out. Once you develop a good grasp of what work is valuable, be ruthless in prioritizing it. The engineers who are great at this have consistently high ratings, great WLB, and thrive for years on end. I'm talking IC4 and I'm talking IC8+.
The way to understand what work is valuable is the same way you learn the e2e infra. And it's not in any Wiki.
To understand the infra and to understand Impact, start by talking to people. Schedule some time with another human, chart out what you currently understand about the infra, then ask them to tell you all the ways in which you are wrong. Put 15m on your manager's manager's manager's calendar and ask them what success looks like for them. Or share what you're working on and ask them what an outstanding (GE+) outcome looks like from their point-of-view.
Finally, Boz has a great onboarding algorithm: https://boz.com/articles/career-cold-start