They give you a take-home assignment to optimize a software. The objective was the software should perform below a certain time limit. I sent the solution knowing It works well on my dev machine. The reviewer got back to me telling me that I must be using some kind of latest-gen overclocked hardware to get this result! I decided to give it another try and did it again using another industry-standard algorithm to make it even run faster (~2x). In the end, after weeks of waiting, I got a rejection email stating they were not satisfied with the speed! It seems that they only care that the software runs below a certain time on their own machine, and the target hardware specs are not even provided! Which is a very flawed expectation.