buying ram with higher speeds does not matter a ton. in general computing tasks, even in high-end video editing ram speed does not play a very big-roll. memory speed means faster memory operations. where the memory amount is responsible for data processing. integrated graphics will benefit from higher speeds because of faster memory operations rate, but if you use a separate GPU, then it will make a really small effect on the performance. some demanding AAA games will benefit from higher speeds, the difference is usually 20-25% between 2400MHz and 4000MHz ram. but it will just give you benefit of just 2-3 FPS.
i recommend you more RAM amounts for much better performance, a 4000MHz 8GB module is not as good as 16 GB 2400 in terms of...