I posted my experience here: Julia's applicable context is getting narrower over time? - #5 by Satvik . In short, I was able to take Python code that we’d spent ~200 hours optimizing, and make a faster Julia version in less than a week, my first time using Julia.
Julia is fast by default, but also has much stronger profiling tools, which makes optimization easy, as well as much better multithreading, which enables many optimizations that just wouldn’t be possible in Python.