You are likely hitting two constraints affecting fps.
The first is that an 800kbps LED has a data rate limitation of about 33k pixels a second with standard 24 bit rgb pixels. That’s a theoretical fps limit of 23 fps for 1440 LEDs just to get the data out.
The next is the cpu rendering, and how this works with ws2812 compatibles with the current driver. The 48k pixels a second is average for the shipping patterns. That gives a theoretical average fps around 33 for 1440 pixels. But the ws2812 driver doesn’t pipeline (yet). So rendering and data happen sequentially. What you have is a frame that takes 1/33 seconds to render then 1/23 seconds to send. Adding these gives you about 13fps. 1/(1/33 + 1/23). Again, that’s a gross average for the shipping patterns, some would be slower, and some should be faster but no faster than the data would allow.
The current best/easy way to get around both issues is to throw in an output expander. The expander has a data rate around 66k pixels a second and allows Pixelblaze to pipeline rendering. You’d need to split up the LEDs into at least 2 parts, and drive each from an expander output, effectively doubling the pixel data rate of the system. Plus the expander driver allows Pixelblaze to pipeline render again, and you’d most likely be limited only by the cpu rendering, getting 33 fps on average with a max around 45.
Past that adding more pixelblazes and further splitting up the LEDs would help. I’d still use expanders, otherwise two PB would only get you around 26 fps. With expanders and two PB you’d get average around 66 with max of 90 fps.
Some more good news for you, I’ve recently been rewriting all of the drivers and have a pipelined ws2812 that can render in parallel, and would bump up the single PB (no expander) system with 1440 LEDs to 23 fps, often limited by the data bandwidth, and 46 for two PBs with that split up. Not as good as a pair of PBs with expanders but might fall within your requirements.
I can get you a beta build with the new driver if you want to give it a spin.