I think wondershaper was good at the beginning of the 2000s (2002 - 2006), but it is not a viable solution when modern equipments and bandwidths are in use (I found a better explanation than I intended to reply with at http://web.archive.org/web/20160428162546/http://www.bufferbloat.net/projects/cerowrt/wiki/Wondershaper_Must_Die
I am not very sure about db cache, but it seems that it might allow devices with lower RAM specs to run the daemon(s) without too much swapping... it's an interesting suggestion if it turns out to be possible, but one must take into account the size of the blockchain and the way buffers are allocated by the OS... Anyway. it seems that there is work done to replace BerkeleyDB in Bitcoin (and possibly other relevant alts), so it might be less than optimal to address this now.
The LCD support depends on device and the graphics driver's quality/configurability. AFAIK Pine64 already has a LCD display for sale. Not sure about RasPi. I admit I've fallen a bit behind the news