String eval is always slow, and it's generally recommended to avoid them when possible on any platform. It's particularly slow on an Rpi, because Rpis are also slow.
A RAM disk is not a bad idea if you can spare the memory, but I don't think it will be particularly helpful in your case. Since the loadup time at boot is what matters to you, you'll just move that time from the "perl" invocation to the copy command. You *might* see some gains by loading the modules all together with PAR, but that could easily move the problem from I/O to the CPU (due to decompression).
The first place I would look is making sure you have a good power supply, and the second place is making sure you have a quality SD card.
"There is no shame in being self-taught, only in not trying to learn in the first place." -- Atrus, Myst: The Book of D'ni.