I don't know LEDE 17.01.7 will be any faster than the stock firmware. However, you may run into a space issue -- the 4MB flash may not fit the firmware + drivers for your AK40v (I'm not sure what is needed and how much space it will take up). You can certainly try it, but if you run out of space, it would require an extroot process to give you more space, and that would require a USB hub to facilitate connecting both a USB flash drive and your AK40v.
A better solution in all respects would be to consider purchasing a more recent, more powerful, and aster device. The successor to the MR3020 is the TL-WR902AC. It is 8/64 and supports 802.11ac. There are also other devices such as several from GL-Inet that are similar and have even more flash and RAM.