I have replaced my SD card but didn’t find that it really made a massive difference. I do like it for the added storage however and would still recommend it if you use a lot of samples. It is not a hard modification to do though, it just requires flashing the Organelle operating system onto a new SD card but you will be starting your system from scratch so I would back your patches up to a USB stick and transfer it later.
The only thing that I found that it may have helped with is cutting down my loading time when opening Orhack or loading modules. It may also have helped with loading times for loading in different kits, and samples but it doesn’t really have any huge effects on CPU. My best advice is use multicore modules as much as possible, use single threaded modules as least as possible, and if you are using Orhack, put your reverb into the sends. If you find yourself still needing more juice, I would check out this thread.
This shows you how you can overclock your organelle to squeeze additional cycles out of your CPU but be warned, this does immediately void your warranty and may damage your Organelle. I have done this modification to my Organelle and used the same heat sync as @RPLKTR and am able to run a maxed out Orhack session except in rare cases where I am reliant on single threaded modules. I would definitely recommend monitoring your CPU temperature for a few days to make sure you installed the heat sync correctly. I did this mod the day after my Organelle’s warranty expired but I am very happy with how it has turned out!