Raid configuration expert recommendation

I'm switching from raid 10 to raid 5 (need more space) and I hope someone with experience can take a look at my settings.

Here is my set up on an lsi 9271-8iCC:
- Raid 1 ssd cache 90G
- Raid 5 4x3TB

Copying 220G of big files performance is around 700Mb/s for a while then dips significantly. I'm assuming this is because the small cache layer, so the performance might be fine...

So here are my settings, which is what I'm hoping to get some guidance on. Thansks a lot!
Raid 5 Config:

Cache (raid 1) config: